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• SQL SERVER – Discard Results After Query Execution – SSMS

  - by pinaldave

  The first thing I do any day is to turn on the computer. Today I woke up and as soon as I turned on the computer I saw a chat message from a friend. He was a bit confused and wanted me to help him. Just as usual I am keeping the relevant conversation in focus and documenting our conversation as chat. Let us call him Ajit. Ajit: Pinal, every time I run a query there is no result displayed in the SSMS but when I run the query in my application it works and returns an appropriate result. Pinal:  Have you tried with different parameters? Ajit: Same thing. However, it works from another computer when I connect to the same server with the same query parameters? Pinal: What? That is new and I believe it is something to do with SSMS and not with the server. Send me screenshot please. Ajit: I believe so, let me send you a screenshot, Pinal: (looking at the screenshot) Oh man, there is no result-tab at all. Ajit: That is what the problem is. It does not have the tab which displays the result. This works just fine from another computer. Pinal: Have you referred Nakul’s blog post – SSMS – Query result options – Discard result after query executes, that talks about setting which can discard the query results after execution. (After a while) Ajit: I think it seems like on the computer where I am running the query my SSMS seems to have the option enabled related to discarding results. I fixed it by following Nakul’s blog post. Pinal: Great! Quite often I get the question what is the importance of the feature. Let us first see how to turn on or turn off this feature in SQL Server Management Studio 2012. In SSMS 2012 go to Tools >> Options >> Query Results > SQL Server >> Results to Grid >> Discard Results After Query Execution. When enabled this option will discard results after the execution. The advantage of disabling the option is that it will improve the performance by using less memory. However the real question is why would someone enable or disable the option. What are the cases when someone wants to run the query but do not care about the result? Matter of the fact, it does not make sense at all to run query and not care about the result. The matter of the fact, I can see quite a few reasons for using this option. I often enable this option when I am doing performance tuning exercise. During performance tuning exercise when I am working with execution plans and do not need results to verify every time or when I am tuning Indexes and its effect on execution plan I do not need the results. In this kind of situations I do keep this option on and discard the results. It always helps me big time as in most of the performance tuning exercise I am dealing with huge amount of the data and dealing with this data can be expensive. Nakul’s has done the experiment here already but I am going to repeat the same again using AdventureWorks Database. Run following T-SQL Script with and without enabling the option to discard the results. USE AdventureWorks2012 GO SELECT * FROM Sales.SalesOrderDetail GO 10 After enabling Discard Results After Query Execution After disabling Discard Results After Query Execution Well, this is indeed a good option when someone is debugging the execution plan or does not want the result to be displayed. Please note that this option does not reduce IO or CPU usage for SQL Server. It just discards the results after execution and a good help for debugging on the development server. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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• SQLAuthority News – Book Signing Event – SQLPASS 2011 Event Log

  - by pinaldave

  I have been dreaming of writing book for really long time, and I finally got the chance – in fact, two chances!  I recently wrote two books: SQL Programming Joes 2 Pros: Programming and Development for Microsoft SQL Server 2008 [Amazon] | [Flipkart] | [Kindle] and SQL Wait Stats Joes 2 Pros: SQL Performance Tuning Techniques Using Wait Statistics, Types & Queues [Amazon] | [Flipkart] | [Kindle].  I had a lot of fun writing these two books, even though sometimes I had to sacrifice some family time and time for other personal development to write the books. The good side of writing book is that when the efforts put in writing books are recognize by books readers and kind organizations like expressor studio. Book Signing Event Book writing is a complex process.  Even after you spend months, maybe years, writing the material you still have to go through the editing and fact checking processes.  And, once the book is out there, there is no way to take back all the copies to change mistakes or add something you forgot.  Most of the time it is a one-way street. Book Signing Event Just like every author, I had a dream that after the books were written, they would be loved by people and gain acceptance by an audience. My first book, SQL Programming Joes 2 Pros: Programming and Development for Microsoft SQL Server 2008, is extremely popular because it helps lots of people learn various fundamental topics. My second book covers beginning to learn SQL Server Wait Stats, which is a relatively new subject. This book has had very good acceptance in the community. Book Signing Event Helping my community is my primary focus, so I was happy to see this year’s SQLPASS tag line: ‘This is a Community.‘ At the event, the expressor studio guys came up with a very novel idea. They had previously used my books and they had found them very useful. They got 100 copies of the book and decided to give it away to community folks. They invited me and my co-author Rick Morelan to hold a book signing event. We did a book signing on Thursday between 1 pm and 2 pm. Book Signing Event This event was one of the best events for me. This was my first book signing event outside of India. I reached the book signing location around 20 minutes before the scheduled time and what I saw was a big line for the book signing event. I felt very honored looking at the crowd and all the people around the event location. I felt very humbled when I saw some of my very close friends standing in the line to get my signature. It was really heartwarming to see so many enthusiasts waiting for more than an hour to get my signature. While standing in line I had the chance to have a conversation with every single person who showed up for the signature. I made sure that I repeated every single name and wrote it in every book with my signature. There is saying that if we write a name once we will remember it forever. I want to remember all of you who saw me at the book signing. Your comments were wonderful, your feedback was amazing and you were all very supportive. Book Signing Event I have made a note of every conversation I had with all of you when I was signing the books. Once again, I just want to express my thanks for coming to my book signing event. The whole experience was very humbling. On the top of it, I want to thank the expressor studio people who made it possible, who organized the whole signing event. I am so thankful to them for facilitating the whole experience, which is going to be hard to beat by any future experience. My books Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL PASS, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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• SQL SERVER – Another lesser known feature of SQL Server Management Studio 2012 – Guest Post by Balmukund Lakhani

  - by Pinal Dave

  This is a fantastic blog post from my dear friend Balmukund ( blog | twitter | facebook ). He had presented a fantastic session in our last UG and there were lots of requests from attendees that he blogs about it. Well, here is the blog post about the same very popular UG session. Let us read the entire blog post in the voice of the Balmukund himself. In one of my previous guest blog on SQL Authority, I wrote about “Additional Connection Parameter” tab of login screen in SQL Server Management Studio (a.k.a. SSMS). On the similar lines, this blog is going to show little less known new feature of login main screen (“Connect to Server”) of SSMS 2012. You might have seen below screen countless times and you might wonder what is there is blog about in this simple screen. Well, continue reading and you would get the answer. Many times, DBA have to login to production server from non-regular machine, may be a developer’s workstation. Once you login to SQL, do your work and close the management studio. Do you know that your server name is saved in management studio? Of course, very useful feature because you may not like to type server name/IP address every time. Whatever servers you have connected, it would be stored by management studio. But sometime, it’s annoying! What you would do if you want SQL Server Management Studio to forget “all” the servers listed in drop down of Server name? To do that, you need to know how and where it’s stored. You can use one of my favorite tool from sysinternals called Process Monitor (also known as ProcMon) and easily figure out that this is stored in a file under your windows user profile. Below is the file in SQL 2008 R2 Management Studio. %appdata%\Microsoft\Microsoft SQL Server\100\Tools\Shell\SqlStudio.bin For SQL Server 2012, here is what we can see in ProcMon So, the path is %appdata%\Microsoft\Microsoft SQL Server\110\Tools\Shell\SqlStudio.bin So far, you might wonder, where is the new feature? I have been asked by many users to delete entries from SSMS “Connect to Server” server name list. Well, unofficially, you can delete the file directly which we found via ProcMon. Note that delete file to get rid of server list is not officially supported by Microsoft. Better way to achieve this is provided in SSMS 2012. To delete the servers from the list, highlight the name we want to delete (via keyboard or mouse) and then press delete key via keyboard. We can’t be multi-select and has to be done one by one. We can delete as many entries we want. I have delete few from first screenshot taken and here is the modified version. This is not available in SQL 2008 R2 and its previous version. This came from feedback given to SQL Server Product group. Hope you have learned something new today! Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Speed Up! – Parallel Processes and Unparalleled Performance – TechEd 2012 India

  - by pinaldave

  TechEd India 2012 is just around the corner and I will be presenting there on two different session. SQL Server Performance Tuning is a very challenging subject that requires expertise in Database Administration and Database Development. I always have enjoyed talking about SQL Server Performance tuning subject. Just like doctors I like to call my every attempt to improve the performance of SQL Server queries and database server as a practice too. I have been working with SQL Server for more than 8 years and I believe that many of the performance tuning concept I have mastered. However, performance tuning is not a simple subject. However there are occasions when I feel stumped, there are occasional when I am not sure what should be the next step. When I face situation where I cannot figure things out easily, it makes me most happy because I clearly see this as a learning opportunity. I have been presenting in TechEd India for last three years. This is my fourth time opportunity to present a technical session on SQL Server. Just like every other year, I decided to present something different, something which I have spend years of learning. This time, I am going to present about parallel processes. It is widely believed that more the CPU will improve performance of the server. It is true in many cases. However, there are cases when limiting the CPU usages have improved overall health of the server. I will be presenting on the subject of Parallel Processes and its effects. I have spent more than a year working on this subject only. After working on various queries on multi-CPU systems I have personally learned few things. In coming TechEd session, I am going to share my experience with parallel processes and performance tuning. Session Details Title: Speed Up! – Parallel Processes and Unparalleled Performance (Add to Calendar) Abstract: “More CPU More Performance” – A  very common understanding is that usage of multiple CPUs can improve the performance of the query. To get maximum performance out of any query – one has to master various aspects of the parallel processes. In this deep dive session, we will explore this complex subject with a very simple interactive demo. An attendee will walk away with proper understanding of CX_PACKET wait types, MAXDOP, parallelism threshold and various other concepts. Date and Time: March 23, 2012, 12:15 to 13:15 Location: Hotel Lalit Ashok - Kumara Krupa High Grounds, Bengaluru – 560001, Karnataka, India. Add to Calendar Please submit your questions in the comments area and I will be for sure discussing them during my session. If I pick your question to discuss during my session, here is your gift I commit right now – SQL Server Interview Questions and Answers Book. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology Tagged: TechEd, TechEdIn

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• SQL SERVER – Quiz and Video – Introduction to Hierarchical Query using a Recursive CTE

  - by pinaldave

  This blog post is inspired from SQL Queries Joes 2 Pros: SQL Query Techniques For Microsoft SQL Server 2008 – SQL Exam Prep Series 70-433 – Volume 2.[Amazon] | [Flipkart] | [Kindle] | [IndiaPlaza] This is follow up blog post of my earlier blog post on the same subject - SQL SERVER – Introduction to Hierarchical Query using a Recursive CTE – A Primer. In the article we discussed various basics terminology of the CTE. The article further covers following important concepts of common table expression. What is a Common Table Expression (CTE) Building a Recursive CTE Identify the Anchor and Recursive Query Add the Anchor and Recursive query to a CTE Add an expression to track hierarchical level Add a self-referencing INNER JOIN statement Above six are the most important concepts related to CTE and SQL Server.  There are many more things one has to learn but without beginners fundamentals one can’t learn the advanced  concepts. Let us have small quiz and check how many of you get the fundamentals right. Quiz 1) You have an employee table with the following data. EmpID FirstName LastName MgrID 1 David Kennson 11 2 Eric Bender 11 3 Lisa Kendall 4 4 David Lonning 11 5 John Marshbank 4 6 James Newton 3 7 Sally Smith NULL You need to write a recursive CTE that shows the EmpID, FirstName, LastName, MgrID, and employee level. The CEO should be listed at Level 1. All people who work for the CEO will be listed at Level 2. All of the people who work for those people will be listed at Level 3. Which CTE code will achieve this result? WITH EmpList AS (SELECT Boss.EmpID, Boss.FName, Boss.LName, Boss.MgrID, 1 AS Lvl FROM Employee AS Boss WHERE Boss.MgrID IS NULL UNION ALL SELECT E.EmpID, E.FirstName, E.LastName, E.MgrID, EmpList.Lvl + 1 FROM Employee AS E INNER JOIN EmpList ON E.MgrID = EmpList.EmpID) SELECT * FROM EmpList WITH EmpListAS (SELECT EmpID, FirstName, LastName, MgrID, 1 as Lvl FROM Employee WHERE MgrID IS NULL UNION ALL SELECT EmpID, FirstName, LastName, MgrID, 2 as Lvl ) SELECT * FROM BossList WITH EmpList AS (SELECT EmpID, FirstName, LastName, MgrID, 1 as Lvl FROM Employee WHERE MgrID is NOT NULL UNION SELECT EmpID, FirstName, LastName, MgrID, BossList.Lvl + 1 FROM Employee INNER JOIN EmpList BossList ON Employee.MgrID = BossList.EmpID) SELECT * FROM EmpList 2) You have a table named Employee. The EmployeeID of each employee’s manager is in the ManagerID column. You need to write a recursive query that produces a list of employees and their manager. The query must also include the employee’s level in the hierarchy. You write the following code segment: WITH EmployeeList (EmployeeID, FullName, ManagerName, Level) AS ( –PICK ANSWER CODE HERE ) SELECT EmployeeID, FullName, ” AS [ManagerID], 1 AS [Level] FROM Employee WHERE ManagerID IS NULL UNION ALL SELECT emp.EmployeeID, emp.FullName mgr.FullName, 1 + 1 AS [Level] FROM Employee emp JOIN Employee mgr ON emp.ManagerID = mgr.EmployeeId SELECT EmployeeID, FullName, ” AS [ManagerID], 1 AS [Level] FROM Employee WHERE ManagerID IS NULL UNION ALL SELECT emp.EmployeeID, emp.FullName, mgr.FullName, mgr.Level + 1 FROM EmployeeList mgr JOIN Employee emp ON emp.ManagerID = mgr.EmployeeId Now make sure that you write down all the answers on the piece of paper. Watch following video and read earlier article over here. If you want to change the answer you still have chance. Solution 1) 1 2) 2 Now compare let us check the answers and compare your answers to following answers. I am very confident you will get them correct. Available at USA: Amazon India: Flipkart | IndiaPlaza Volume: 1, 2, 3, 4, 5 Please leave your feedback in the comment area for the quiz and video. Did you know all the answers of the quiz? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQLAuthority News – Monthly list of Puzzles and Solutions on SQLAuthority.com

  - by pinaldave

  This month has been very interesting month for SQLAuthority.com we had multiple and various puzzles which everybody participated and lots of interesting conversation which we have shared. Let us start in latest puzzles and continue going down. There are few answers also posted on facebook as well. SQL SERVER – Puzzle Involving NULL – Resolve – Error – Operand data type void type is invalid for sum operator This puzzle involves NULL and throws an error. The challenge is to resolve the error. There are multiple ways to resolve this error. Readers has contributed various methods. Few of them even have supplied the answer why this error is showing up. NULL are very important part of the database and if one of the column has NULL the result can be totally different than the one expected. SQL SERVER – T-SQL Scripts to Find Maximum between Two Numbers I modified script provided by friend to find greatest number between two number. My script has small bug in it. However, lots of readers have suggested better scripts. Madhivanan has written blog post on the subject over here. SQL SERVER – BI Quiz Hint – Performance Tuning Cubes – Hints This quiz is hosted on my friend Jacob‘s site. I have written many hints how one can tune cubes. Now one can take part here and win exciting prizes. SQL SERVER – Solution – Generating Zero Without using Any Numbers in T-SQL Madhivanan has asked very interesting question on his blog about How to Generate Zero without using Any Numbers in T-SQL. He has demonstrated various methods how one can generate Zero. I asked the same question on blog and got many interesting answers which I have shared. SQL SERVER – Solution – Puzzle – Statistics are not Updated but are Created Once I have to accept that this was most difficult puzzle. In this puzzle I have asked even though settings are correct, why statistics of the tables are not getting updated. In this puzzle one is tested with various concepts 1) Indexes, 2) Statistics, 3) database settings etc. There are multiple ways of solving this puzzles. It was interesting as many took interest but only few got it right. SQL SERVER – Question to You – When to use Function and When to use Stored Procedure This is rather straight forward question and not the typical puzzle. The answers from readers are great however, still there is chance of more detailed answers. SQL SERVER – Selecting Domain from Email Address I wrote on selecting domains from email addresses. Madhivanan makes puzzle out of a simple question. He wrote a follow-up post over here. In his post he writes various way how one can find email addresses from list of domains. Well, this is not a puzzle but amazing Guest Post by Feodor Georgiev who has written on subject Job Interviewing the Right Way (and for the Right Reasons). An article which everyone should read. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• SQL SERVER – Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012

  - by pinaldave

  SQL Server 2012 introduces new analytical function LEAD() and LAG(). This functions accesses data from a subsequent row (for lead) and previous row (for lag) in the same result set without the use of a self-join . It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. Let us fun following query. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result. When we look at above resultset it is very clear that LEAD function gives us value which is going to come in next line and LAG function gives us value which was encountered in previous line. If we have to generate the same result without using this function we will have to use self join. In future blog post we will see the same. Let us explore this function a bit more. This function not only provide previous or next line but it can also access any line before or after using offset. Let us fun following query, where LEAD and LAG function accesses the row with offset of 2. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID,2) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID,2) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result. You can see the LEAD and LAG functions  now have interval of  rows when they are returning results. As there is interval of two rows the first two rows in LEAD function and last two rows in LAG function will return NULL value. You can easily replace this NULL Value with any other default value by passing third parameter in LEAD and LAG function. Let us fun following query. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID,2,0) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID,2,0) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result, where NULL are now replaced with value 0. Just like any other analytic function we can easily partition this function as well. Let us see the use of PARTITION BY in this clause. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result, where now the data is partitioned by SalesOrderID and LEAD and LAG functions are returning the appropriate result in that window. As now there are smaller partition in my query, you will see higher presence of NULL. In future blog post we will see how this functions are compared to SELF JOIN. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Updating Data in A Columnstore Index

  - by pinaldave

  So far I have written two articles on Columnstore Indexes, and both of them got very interesting readership. In fact, just recently I got a query on my previous article on Columnstore Index. Read the following two articles to get familiar with the Columnstore Index. They will give you a reference to the question which was asked by a certain reader: SQL SERVER – Fundamentals of Columnstore Index SQL SERVER – How to Ignore Columnstore Index Usage in Query Here is the reader’s question: ” When I tried to update my table after creating the Columnstore index, it gives me an error. What should I do?” When the Columnstore index is created on the table, the table becomes Read-Only table and it does not let any insert/update/delete on the table. The basic understanding is that Columnstore Index will be created on the table that is very huge and holds lots of data. If a table is small enough, there is no need to create a Columnstore index. The regular index should just help it. The reason why Columnstore index was needed is because the table was so big that retrieving the data was taking a really, really long time. Now, updating such a huge table is always a challenge by itself. If the Columnstore Index is created on the table, and the table needs to be updated, you need to know that there are various ways to update it. The easiest way is to disable the Index and enable it. Consider the following code: USE AdventureWorks GO -- Create New Table CREATE TABLE [dbo].[MySalesOrderDetail]( [SalesOrderID] [int] NOT NULL, [SalesOrderDetailID] [int] NOT NULL, [CarrierTrackingNumber] [nvarchar](25) NULL, [OrderQty] [smallint] NOT NULL, [ProductID] [int] NOT NULL, [SpecialOfferID] [int] NOT NULL, [UnitPrice] [money] NOT NULL, [UnitPriceDiscount] [money] NOT NULL, [LineTotal] [numeric](38, 6) NOT NULL, [rowguid] [uniqueidentifier] NOT NULL, [ModifiedDate] [datetime] NOT NULL ) ON [PRIMARY] GO -- Create clustered index CREATE CLUSTERED INDEX [CL_MySalesOrderDetail] ON [dbo].[MySalesOrderDetail] ( [SalesOrderDetailID]) GO -- Create Sample Data Table -- WARNING: This Query may run upto 2-10 minutes based on your systems resources INSERT INTO [dbo].[MySalesOrderDetail] SELECT S1.* FROM Sales.SalesOrderDetail S1 GO 100 -- Create ColumnStore Index CREATE NONCLUSTERED COLUMNSTORE INDEX [IX_MySalesOrderDetail_ColumnStore] ON [MySalesOrderDetail] (UnitPrice, OrderQty, ProductID) GO -- Attempt to Update the table UPDATE [dbo].[MySalesOrderDetail] SET OrderQty = OrderQty +1 WHERE [SalesOrderID] = 43659 GO /* It will throw following error Msg 35330, Level 15, State 1, Line 2 UPDATE statement failed because data cannot be updated in a table with a columnstore index. Consider disabling the columnstore index before issuing the UPDATE statement, then rebuilding the columnstore index after UPDATE is complete. */ A similar error also shows up for Insert/Delete function. Here is the workaround. Disable the Columnstore Index and performance update, enable the Columnstore Index: -- Disable the Columnstore Index ALTER INDEX [IX_MySalesOrderDetail_ColumnStore] ON [dbo].[MySalesOrderDetail] DISABLE GO -- Attempt to Update the table UPDATE [dbo].[MySalesOrderDetail] SET OrderQty = OrderQty +1 WHERE [SalesOrderID] = 43659 GO -- Rebuild the Columnstore Index ALTER INDEX [IX_MySalesOrderDetail_ColumnStore] ON [dbo].[MySalesOrderDetail] REBUILD GO This time it will not throw an error while the update of the table goes successfully. Let us do a cleanup of our tables using this code: -- Cleanup DROP INDEX [IX_MySalesOrderDetail_ColumnStore] ON [dbo].[MySalesOrderDetail] GO TRUNCATE TABLE dbo.MySalesOrderDetail GO DROP TABLE dbo.MySalesOrderDetail GO In the next post we will see how we can use Partition to update the Columnstore Index. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Index, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – OVER clause with FIRST _VALUE and LAST_VALUE – Analytic Functions Introduced in SQL Server 2012 – ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING

  - by pinaldave

  Yesterday I had discussed two analytical functions FIRST_VALUE and LAST_VALUE. After reading the blog post I received very interesting question. “Don’t you think there is bug in your first example where FIRST_VALUE is remain same but the LAST_VALUE is changing every line. I think the LAST_VALUE should be the highest value in the windows or set of result.” I find this question very interesting because this is very commonly made mistake. No there is no bug in the code. I think what we need is a bit more explanation. Let me attempt that first. Before you do that I suggest you read yesterday’s blog post as this question is related to that blog post. Now let’s have fun following query: USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO The above query will give us the following result: As per the reader’s question the value of the LAST_VALUE function should be always 114 and not increasing as the rows are increased. Let me re-write the above code once again with bit extra T-SQL Syntax. Please pay special attention to the ROW clause which I have added in the above syntax. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Now once again check the result of the above query. The result of both the query is same because in OVER clause the default ROWS selection is always UNBOUNDED PRECEDING AND CURRENT ROW. If you want the maximum value of the windows with OVER clause you need to change the syntax to UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING for ROW clause. Now run following query and pay special attention to ROW clause again. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Here is the resultset of the above query which is what questioner was asking. So in simple word, there is no bug but there is additional syntax needed to add to get your desired answer. The same logic also applies to PARTITION BY clause when used. Here is quick example of how we can further partition the query by SalesOrderDetailID with this new functions. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us windowed resultset on SalesOrderDetailsID as well give us FIRST and LAST value for the windowed resultset. There are lots to discuss for this two functions and we have just explored tip of the iceberg. In future post I will discover it further deep. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Read Only Files and SQL Server Management Studio (SSMS)

  - by pinaldave

  Just like any other Developer or DBA SQL Server Management Studio is my favorite application. Any any moment of the time I have multiple instances of the same application are open and I am working on it. Recently, I have come across a very interesting feature in SSMS related to “Read Only” files. I believe it is a little unknown feature as well so decided to write a blog about the same. First create a read only SQL file. You can make any file read by Right Click >> Properties >> Select Attribute Read Only. Now open the same file in SQL Server Management Studio. You will find that besides the file name there is a small ‘lock’ icon. This small icon indicates that the file is read only. Now let us attempt to edit the read only file. It will let us edit the file any way we want, however when we attempt to save it, it gives following pop-up value. The options in the pop-up are self explanatory and I liked it. The goal of the read only file is to prevent users to make un-intended changes. However, when a user should have complete control over the user file. User should be aware that the file is read only but if he wants to edit the file or save as a new file the choices should be present in front of it and the pop-up menu precisely captures the same. Now let us check option related to this feature in SSMS. Go to Menu >> Options >> Environment >> Documents You will find the third option which is “Allow editing of read-only files; warn when attempt to save”. In the above scenario it was already checked. Let us uncheck the same and do the same exercise which we have done earlier. I closed all the earlier window to avoid confusion. With the new option selected when I attempt to even modify the Read Only file, it gives me totally different pop up screen. It gives me an option like “Edit In-Memory”, “Make Writeable” etc. When you select “Edit In-Memory” it allows you to edit the file and later you can save as new file – just like the earlier scenario which we have discussed. . If clicked on the Make Writeable it will remove the restriction of the Read Only and file can be edited as pleased. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – UNION ALL and ORDER BY – How to Order Table Separately While Using UNION ALL

  - by pinaldave

  I often see developers trying following syntax while using ORDER BY. SELECT Columns FROM TABLE1 ORDER BY Columns UNION ALL SELECT Columns FROM TABLE2 ORDER BY Columns However the above query will return following error. Msg 156, Level 15, State 1, Line 5 Incorrect syntax near the keyword ‘ORDER’. It is not possible to use two different ORDER BY in the UNION statement. UNION returns single resultsetand as per the Logical Query Processing Phases. However, if your requirement is such that you want your top and bottom query of the UNION resultset independently sorted but in the same resultset you can add an additional static column and order by that column. Let us re-create the same scenario. First create two tables and populated with sample data. USE tempdb GO -- Create table CREATE TABLE t1 (ID INT, Col1 VARCHAR(100)); CREATE TABLE t2 (ID INT, Col1 VARCHAR(100)); GO -- Sample Data Build INSERT INTO t1 (ID, Col1) SELECT 1, 'Col1-t1' UNION ALL SELECT 2, 'Col2-t1' UNION ALL SELECT 3, 'Col3-t1'; INSERT INTO t2 (ID, Col1) SELECT 3, 'Col1-t2' UNION ALL SELECT 2, 'Col2-t2' UNION ALL SELECT 1, 'Col3-t2'; GO If we SELECT the data from both the table using UNION ALL . -- SELECT without ORDER BY SELECT ID, Col1 FROM t1 UNION ALL SELECT ID, Col1 FROM t2 GO We will get the data in following order. However, our requirement is to get data in following order. If we need data ordered by Column1 we can ORDER the resultset ordered by Column1. -- SELECT with ORDER BY SELECT ID, Col1 FROM t1 UNION ALL SELECT ID, Col1 FROM t2 ORDER BY ID GO Now to get the data in independently sorted in UNION ALL let us add additional column OrderKey and use ORDER BY  on that column. I think the description does not do proper justice let us see the example here. -- SELECT with ORDER BY - with ORDER KEY SELECT ID, Col1, 'id1' OrderKey FROM t1 UNION ALL SELECT ID, Col1, 'id2' OrderKey FROM t2 ORDER BY OrderKey, ID GO The above query will give the desired result. Now do not forget to clean up the database by running the following script. -- Clean up DROP TABLE t1; DROP TABLE t2; GO Here is the complete script used in this example. USE tempdb GO -- Create table CREATE TABLE t1 (ID INT, Col1 VARCHAR(100)); CREATE TABLE t2 (ID INT, Col1 VARCHAR(100)); GO -- Sample Data Build INSERT INTO t1 (ID, Col1) SELECT 1, 'Col1-t1' UNION ALL SELECT 2, 'Col2-t1' UNION ALL SELECT 3, 'Col3-t1'; INSERT INTO t2 (ID, Col1) SELECT 3, 'Col1-t2' UNION ALL SELECT 2, 'Col2-t2' UNION ALL SELECT 1, 'Col3-t2'; GO -- SELECT without ORDER BY SELECT ID, Col1 FROM t1 UNION ALL SELECT ID, Col1 FROM t2 GO -- SELECT with ORDER BY SELECT ID, Col1 FROM t1 UNION ALL SELECT ID, Col1 FROM t2 ORDER BY ID GO -- SELECT with ORDER BY - with ORDER KEY SELECT ID, Col1, 'id1' OrderKey FROM t1 UNION ALL SELECT ID, Col1, 'id2' OrderKey FROM t2 ORDER BY OrderKey, ID GO -- Clean up DROP TABLE t1; DROP TABLE t2; GO I am sure there are many more ways to achieve this, what method would you use if you have to face the similar situation? Reference: Pinal Dave (http://blog.sqlauthority.com)   Filed under: Best Practices, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Basic Calculation and PEMDAS Order of Operation

  - by pinaldave

  After thinking a long time, I have decided to write about this blog post. I had no plan to create a blog post about this subject but the amount of conversation this one has created on my Facebook page, I decided to bring up a few of the question and concerns discussed on the Facebook page. There are more than 10,000 comments here so far. There are lots of discussion about what should be the answer. Well, as far as I can tell there is a big debate going on on Facebook, for educational purpose you should go ahead and read some of the comments. They are very interesting and for sure teach some new stuff. Even though some of the comments are clearly wrong they have made some good points and I believe it for sure develops some logic. Here is my take on this subject. I believe the answer is 9 as I follow PEMDAS  Order of Operation. PEMDAS stands for  parentheses, exponents, multiplication, division, addition, subtraction. PEMDAS is commonly known as BODMAS in India. BODMAS stands for Brackets, Orders (ie Powers and Square Roots, etc), Division, Multiplication,  Addition and Subtraction. PEMDAS and BODMAS are almost same and both of them follow the operation order from LEFT to RIGHT. Let us try to simplify above statement using the PEMDAS or BODMAS (whatever you prefer to call). Step 1: 6 ÷ 2 (1+2) (parentheses first) Step 2: = 6 ÷ 2 * (1+2) (adding multiplication sign for further clarification) Step 3: = 6 ÷ 2* (3) (single digit in parentheses – simplify using operator) Step 4: = 6 ÷ 2 * 3 (Remember next Operation should be LEFT to RIGHT) Step 5: = 3 * 3 (because 6 ÷ 2 = 3; remember LEFT to RIGHT) Step 6: = 9 (final answer) Some often find Step 4 confusing and often ended up multiplying 2 and 3 resulting Step 5 to be 6 ÷ 6, this is incorrect because in this case we did not follow the order of LEFT to RIGHT. When we do not follow the order of operation from LEFT to RIGHT we end up with the answer 1 which is incorrect. Let us see what SQL Server returns as a result. I executed following statement in SQL Server Management Studio SELECT 6/2*(1+2) It is clear that SQL Server also thinks that the answer should be 9. Let us go ahead and ask Google what will be the answer of above question in Google I have searched for the following term: 6/2(1+2) The result also says the answer should be 9. If you want a further reference here is a great video which describes why the answer should be 9 and not 1. And here is a fantastic conversation on Google Groups. Well, now what is your take on this subject? You are welcome to share constructive feedback and your answer may be different from my answer. NOTE: A healthy conversation about this subject is indeed encouraged but if there is a single bad word or comment is flaming it will be deleted without any notification (it does not matter how valuable information it contains). Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL – Step by Step Guide to Download and Install NuoDB – Getting Started with NuoDB

  - by Pinal Dave

  Let us take a look at the application you own at your business. If you pay attention to the underlying database for that application you will be amazed. Every successful business these days processes way more data than they used to process before. The number of transactions and the amount of data is growing at an exponential rate. Every single day there is way more data to process than before. Big data is no longer a concept; it is now turning into reality. If you look around there are so many different big data solutions and it can be a quite difficult task to figure out where to begin. Personally, I have been experimenting with a lot of different solutions which allow my database to scale immediately without much hassle while maintaining optimal database performance.  There are for sure some solutions out there, but for many I even have to learn their specific language and there is a lot of new exploration to do. Honestly, what I prefer is a product, which works with the language I know (SQL) and follows all the RDBMS concepts which I am familiar with (ACID etc.). NuoDB is one such solution.  It is an operational NewSQL database built on a patented emergent architecture with full support for SQL and ACID guarantees. In this blog post, I will explore how one can download and install NuoDB database. Step 1: Follow me and go to the NuoDB download page. Simply fill out the form, accept the online license agreement, and you will be taken directly to a page where you can select any platform you prefer to install NuoDB. In my example below, I select the Windows 64-bit platform as it is one of the most popular NuoDB platforms. (You can also run NuoDB on Amazon Web Services but I prefer to install it on my local machine for the purposes of this blog). Step 2: Once you have downloaded the NuoDB installer, double click on it to install it on the Windows platform. Here is the enlarged the icon of the installer. Step 3: Follow the wizard installation, as it is pretty straight forward and easy to do so. I have selected all the options to install as the overall installation is very simple and it does not take up much space. I have installed it on my C drive but you can select your preferred drive. It is quite possible that if you do not have 64 bit Java, it will throw following error. If you face following error, I suggest you to download 64-bit Java from here. Make sure that you download 64-bit Java from following link: http://java.com/en/download/manual.jsp If already have Java 64-bit installed, you can continue with the installation as described in following image. Otherwise, install Java and start from with Step 1. As in my case, I already have 64-bit Java installed – and you won’t believe me when I say that the entire installation of NuoDB only took me around 90 seconds. Click on Finish to end to exit the installation. Step 4: Once the installation is successful, NuoDB will automatically open the following two tabs – Console and DevCenter — in your preferred browser. On the Console tab you can explore various components of the NuoDB solution, e.g. QuickStart, Admin, Explorer, Storefront and Samples. We will see various components and their usage in future blog posts. If you follow these steps in this post, which I have followed to install NuoDB, you will agree that the installation of NuoDB is extremely smooth and it was indeed a pleasure to install a database product with such ease. If you have installed other database products in the past, you will absolutely agree with me. So download NuoDB and install it today, and in tomorrow’s blog post I will take the installation to the next level. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: NuoDB

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• SQL SERVER – Puzzle to Win Print Book – Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY

  - by pinaldave

  Some time an interesting feature and smart audience makes total difference at places. From last two days, I have been writing on SQL Server 2012 feature FIRST_VALUE and LAST_VALUE. Please read following post before I continue today as this question is based on the same. Introduction to FIRST_VALUE and LAST_VALUE Introduction to FIRST_VALUE and LAST_VALUE with OVER clause As a comment of the second post I received excellent question from Nilesh Molankar. He asks what will happen if we change few things in the T-SQL. I really like this question as this kind of questions will make us sharp and help us perform in critical situation in need. We recently publish SQL Server Interview Questions book. I promise that in future version of this book, we will for sure include this question. Instead of repeating his question, I am going to ask something very similar to his question. Let us first run following query (read yesterday’s blog post for more detail): USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Here is the resultset of the above query. Now let us change the ORDER BY clause of OVER clause in above query and see what is the new result. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY OrderQty ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY OrderQty ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Now let us see the result and ready for interesting question: Puzzle You can see that row number 2, 3, 4, and 5 has same SalesOrderID = 43667. The FIRST_VALUE is 78 and LAST_VALUE is 77. Now if these function was working on maximum and minimum value they should have given answer as 77 and 80 respectively instead of 78 and 77. Also the value of FIRST_VALUE is greater than LAST_VALUE 77. Why? Explain in detail. Hint Let me give you a simple hint. Just for simplicity I have changed the order of columns selected in the SELECT and ORDER BY (at the end). This will not change resultset but just order of the columns as well order of the rows. However, the data remains the same. USE AdventureWorks GO SELECT s.OrderQty,s.SalesOrderID,s.SalesOrderDetailID, FIRST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY OrderQty ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY OrderQty ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.OrderQty,s.SalesOrderID,s.SalesOrderDetailID GO Above query returns following result: Now I am very sure all of you have figured out the solution. Here is the second hint – pay attention to row 2, 3, 4, and 10. Hint2 T-SQL Enhancements: FIRST_VALUE() and LAST_VALUE() MSDN: FIRST_VALUE and LAST_VALUE Rules Leave a comment with your detailed answer by Nov 15′s blog post. Open world-wide (where Amazon ships books) If you blog about puzzle’s solution and if you win, you win additional surprise gift as well. Prizes Print copy of my new book SQL Server Interview Questions Amazon|Flipkart If you already have this book, you can opt for any of my other books SQL Wait Stats [Amazon|Flipkart|Kindle] and SQL Programming [Amazon|Flipkart|Kindle]. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Performance Tuning Resolution

  - by pinaldave

  This blog post is written in response to T-SQL Tuesday hosted by MidnightDBAs. Taking resolutions is such an interesting subject. I think just like records, these are broken way more often. I find this is the funniest thing as we all take resolutions every year but not every year, we can manage to keep them. Well, does it mean we should not take resolutions? In fact I support resolutions. Every year, I take a resolution that I will strive reduce my body weight and I usually manage to keep eating healthy till the end of January. When February begins, I begin to loose focus from my goal and as March starts, the “As usual” eating habits begin. Looking at the positive side, what would happen if every year I do not eat healthy in January, I think that might cause terrible consequences to my health in the long run. So keeping resolutions is a good practise and following them to the extent one can is commendable. Let us come back to the world of SQL Server. What is my resolution for year 2011 for SQL Server? There are many, I am going to list three of very important resolutions that I have taken this new year over here. To understand SQL Server Performance Tuning at a deeper Level I think I am already half way through. I have been being very much busy during any given month doing hands-on performance tuning for at least 12 days on an average. That means, I am doing this activity for almost doing 2 weeks a month. I believe that I have a good understanding of the subject. Note that the word that I have used is “good,” and not “best.” There are often cases when I am stumped, and I have no clue of what to do next. Then, I usually go for my “trial and error” method - whichever method works, I make sure to keep a note on my blog. My goal is that I should never ever go for the trial and error method again to achieve the same solution. I should know the solution right away when I see the problem. I do understand that Performance Tuning can be a strange animal at times and one cannot guess the right step every time. However, aiming a high goal never hurts and I am going to learn more and more in this focused area. Going further from Basic BI understanding I do fairly decent with BI concepts. I know the nbasics of SSIS, SSRS, SSAS, PowerPivot and SharePoint (and few other things MDS, StreamInsight, etc). However, I still consider myself as a beginner. I do not have hands-on experience like many other BI Gurus around. I think I want to take my learning further in this direction. I do not want to be a BI expert as the first step but the goal is to move ahead from basic level towards an advanced level. I am going to start presenting in User Group Sessions and other places on this subject. When I have to prepare new subject for presentations, I think I force myself to learn more. I am committed to learn a bit more in this direction. Learning new features SQL Server 2011 Denali This is new thing from “Microsoft” for all the SQL Geeks. I am eagerly waiting for final product later this year and I am planning to learn it well. I think if I follow my above two goals, I think this goal will be automatically covered. I am eager and excited for this new offering from Microsoft. I guess, these are my resolutions; may be next year about the same time, I must revisit this post and see how much successful I am in following my goal. On a lighter note, I am particularly fan of following cartoon strip (Courtesy: Calvin and Hobbes). I think when we cannot resolve our resolutions, we tend to act like Calvin. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Introduction to Big Data – Guest Post

  - by pinaldave

  BIG Data – such a big word – everybody talks about this now a days. It is the word in the database world. In one of the conversation I asked my friend Jasjeet Sigh the same question – what is Big Data? He instantly came up with a very effective write-up.  Jasjeet is working as a Technical Manager with Koenig Solutions. He leads the SQL domain, and holds rich IT industry experience. Talking about Koenig, it is a 19 year old IT training company that offers several certification choices. Some of its courses include SharePoint Training, Project Management certifications, Microsoft Trainings, Business Intelligence programs, Web Design and Development courses etc. Big Data, as the name suggests, is about data that is BIG in nature. The data is BIG in terms of size, and it is difficult to manage such enormous data with relational database management systems that are quite popular these days. Big Data is not just about being large in size, it is also about the variety of the data that differs in form or type. Some examples of Big Data are given below : Scientific data related to weather and atmosphere, Genetics etc Data collected by various medical procedures, such as Radiology, CT scan, MRI etc Data related to Global Positioning System Pictures and Videos Radio Frequency Data Data that may vary very rapidly like stock exchange information Apart from difficulties in managing and storing such data, it is difficult to query, analyze and visualize it. The characteristics of Big Data can be defined by four Vs: Volume: It simply means a large volume of data that may span Petabyte, Exabyte and so on. However it also depends organization to organization that what volume of data they consider as Big Data. Variety: As discussed above, Big Data is not limited to relational information or structured Data. It can also include unstructured data like pictures, videos, text, audio etc. Velocity:  Velocity means the speed by which data changes. The higher is the velocity, the more efficient should be the system to capture and analyze the data. Missing any important point may lead to wrong analysis or may even result in loss. Veracity: It has been recently added as the fourth V, and generally means truthfulness or adherence to the truth. In terms of Big Data, it is more of a challenge than a characteristic. It is difficult to ascertain the truth out of the enormous amount of data and the one that has high velocity. There are always chances of having un-precise and uncertain data. It is a challenging task to clean such data before it is analyzed. Big Data can be considered as the next big thing in the IT sector in terms of innovation and development. If appropriate technologies are developed to analyze and use the information, it can be the driving force for almost all industrial segments. These include Retail, Manufacturing, Service, Finance, Healthcare etc. This will help them to automate business decisions, increase productivity, and innovate and develop new products. Thanks Jasjeet Singh for an excellent write up.  Jasjeet Sign is working as a Technical Manager with Koenig Solutions. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Database, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Big Data

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• SQL SERVER – Select the Most Optimal Backup Methods for Server

  - by pinaldave

  Backup and Restore are very interesting concepts and one should be very much with the concept if you are dealing with production database. One never knows when a natural disaster or user error will surface and the first thing everybody wants is to get back on point in time when things were all fine. Well, in this article I have attempted to answer a few of the common questions related to Backup methodology. How to Select a SQL Server Backup Type In order to select a proper SQL Server backup type, a SQL Server administrator needs to understand the difference between the major backup types clearly. Since a picture is worth a thousand words, let me offer it to you below. Select a Recovery Model First The very first question that you should ask yourself is: Can I afford to lose at least a little (15 min, 1 hour, 1 day) worth of data? Resist the temptation to save it all as it comes with the overhead – majority of businesses outside finances can actually afford to lose a bit of data. If your answer is YES, I can afford to lose some data – select a SIMPLE (default) recovery model in the properties of your database, otherwise you need to select a FULL recovery model. The additional advantage of the Full recovery model is that it allows you to restore the data to a specific point in time vs to only last backup time in the Simple recovery model, but it exceeds the scope of this article Backups in SIMPLE Recovery Model In SIMPLE recovery model you can select to do just Full backups or Full + Differential. Full Backup This is the simplest type of backup that contains all information needed to restore the database and should be your first choice. It is often sufficient for small databases, but note that it makes a big impact on the performance of your database Full + Differential Backup After Full, Differential backup picks up all of the changes since the last Full backup. This means if you made Full, Diff, Diff backup – the last Diff backup contains all of the changes and you don’t need the previous Differential backup. Differential backup is obviously smaller and carries less performance overhead Backups in FULL Recovery Model In FULL recovery model you can select Full + Transaction Log or Full + Differential + Transaction Log backup. You have to create Transaction Log backup, because at that time the log is being truncated. Otherwise your Transaction Log will grow uncontrollably. Full + Transaction Log Backup You would always need to perform a Full backup first. Then a series of Transaction log backup. Note that (in contrast to Differential) you need ALL transactions to log since the last Full of Diff backup to properly restore. Transaction log backups have the smallest performance overhead and can be performed often. Full + Differential + Transaction Log Backup If you want to ease the performance overhead on your server, you can replace some of the Full backup in the previous scenario with Differential. You restore scenario would start from Full, then the Last Differential, then all of the remaining transactions log backups Typical backup Scenarios You may say “Well, it is all nice – give me the examples now”. As you may already know, my favorite SQL backup software is SQLBackupAndFTP. If you go to Advanced Backup Schedule form in this program and click “Load a typical backup plan…” link, it will give you these scenarios that I think are quite common – see the image below. The Simplest Way to Schedule SQL Backups I hate to repeat myself, but backup scheduling in SQL agent leaves a lot to be desired. I do not know the simple way to schedule your SQL server backups than in SQLBackupAndFTP – see the image below. The whole backup scheduling with compression, encryption and upload to a Network Folder / HDD / NAS Drive / FTP / Dropbox / Google Drive / Amazon S3 takes just a few minutes – see my previous post for the review. Final Words This post offered an explanation for major backup types only. For more complicated scenarios or to research other options as usually go to MSDN. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Backup and Restore, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Why Do We Need Master Data Management – Importance and Significance of Master Data Management (MDM)

  - by pinaldave

  Let me paint a picture of everyday life for you.  Let’s say you and your wife both have address books for your groups of friends.  There is definitely overlap between them, so that you both have the addresses for your mutual friends, and there are addresses that only you know, and some only she knows.  They also might be organized differently.  You might list your friend under “J” for “Joe” or even under “W” for “Work,” while she might list him under “S” for “Joe Smith” or under your name because he is your friend.  If you happened to trade, neither of you would be able to find anything! This is where data management would be very important.  If you were to consolidate into one address book, you would have to set rules about how to organize the book, and both of you would have to follow them.  You would also make sure that poor Joe doesn’t get entered twice under “J” and under “S.” This might be a familiar situation to you, whether you are thinking about address books, record collections, books, or even shopping lists.  Wherever there is a lot of data to consolidate, you are going to run into problems unless everyone is following the same rules. I’m sure that my readers can figure out where I am going with this.  What is SQL Server but a computerized way to organize data?  And Microsoft is making it easier and easier to get all your “addresses” into one place.  In the  2008 version of SQL they introduced a new tool called Master Data Services (MDS) for Master Data Management, and they have improved it for the new 2012 version. MDM was hailed as a major improvement for business intelligence.  You might not think that an organizational system is terribly exciting, but think about the kind of “address books” a company might have.  Many companies have lots of important information, like addresses, credit card numbers, purchase history, and so much more.  To organize all this efficiently so that customers are well cared for and properly billed (only once, not never or multiple times!) is a major part of business intelligence. MDM comes into play because it will comb through these mountains of data and make sure that all the information is consistent, accurate, and all placed in one database so that employees don’t have to search high and low and waste their time. MDM also has operational MDM functions.  This is not a redundancy.  Operational MDM means that when one employee updates one bit of information in the database, for example – updating a new address for a customer, operational MDM ensures that this address is updated throughout the system so that all departments will have the correct information. Another cool thing about MDM is that it features Master Data Services Configuration Manager, which is exactly what it sounds like.  It has a built-in “helper” that lets you set up your database quickly, easily, and with the correct configurations.  While talking about cool features, I can’t skip over the add-in for Excel.  This allows you to link certain data to Excel files for easier sharing and uploading. In summary, I want to emphasize that the scariest part of the database is slowly disappearing.  Everyone knows that a database – one consolidated area for all your data – is a good idea, but the idea of setting one up is daunting.  But SQL Server is making data management easier and easier with features like Master Data Services (MDS). Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Master Data Services, MDM

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• SQLAuthority News – Stay Connected and Social Media

  - by pinaldave

  I think I have finally gotten back my faith in social media. If you are following my blog I am sure you are aware of my views on social media – SQLAuthority News – Social Media Confusion – Twitter, FaceBook, LinkedIn and Me. I was not happy about how social media was evolving. Whenever I go to Twitter, LinkedIn or Facebook, I noticed the same updates everywhere. I just thought I was wasting my time doing the same thing everywhere. I strongly believe that there is no dictator on internet. Nobody has authority over others, everybody can express their ideas as long as it is not violating others privacy and it is not morally wrong. I have decided that instead of trying to improve the world, I should change myself and adjust my needs. Here are few things I have done to relieve my social media confusion. Twitter I un-followed people who were taking up my time with too many updates. I un-followed people who hardly updated at all. I did not follow anybody else’s list, as I have no control over who other people follow. I follow not only serious SQL people but some fun stuff as well. I removed all my friends who were on Facebook and repeating the same updates on Twitter. I engage with them on Facebook. I followed people who are very conversational on Twitter. I let anybody follow me. I update all my blog posts through at least five tweets online. I decided to re-tweet at least five of my favorite tweets of the day, this way I force myself to remain active in the community. Follow me on Twitter! LinkedIn I updated my career and professional info on LinkedIn. I keep my LinkedIn profile updated with my latest jobs and career news. I let anybody connect with me on LinkedIn. I specify my email address in my profile, keeping it easy for those who want to add me. I read all the profile related updates of my connections – it is very valuable to know who is where and what changes are happening. I do not add my personal tweets or comments in LinkedIn profile. I just keep it professional. Link with me at LinkedIn Facebook I use Facebook only for personal friends. I visit all of my friends at regular intervals and make sure that they are really my friends. I often remove my friends from my Twitter list who are sending duplicate updates. I upload my family photos as well as family updates on Facebook, making sure that only my approved friends are able to read my updates. I keep my Facebook very personal and I often chat with my friends on Facebook chat. I am no longer confused about social media and I think I am using it appropriately. As I said, one cannot decide for others how to use social media, you can only decide for yourself. I have finally found my peace with social media. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – A Puzzle Part 4 – Fun with SEQUENCE in SQL Server 2012 – Guess the Next Value

  - by pinaldave

  It seems like every weekend I get a new puzzle in my mind. Before continuing I suggest you read my previous posts here where I have shared earlier puzzles. A Puzzle – Fun with SEQUENCE in SQL Server 2012 – Guess the Next Value  A Puzzle Part 2 – Fun with SEQUENCE in SQL Server 2012 – Guess the Next Value A Puzzle Part 3 – Fun with SEQUENCE in SQL Server 2012 – Guess the Next Value After reading above three posts, I am very confident that you all will be ready for the next set of puzzles now. First execute the script which I have written here. Now guess what will be the next value as requested in the query. USE TempDB GO -- Create sequence CREATE SEQUENCE dbo.SequenceID AS DECIMAL(3,0) START WITH 1 INCREMENT BY -1 MINVALUE 1 MAXVALUE 3 CYCLE NO CACHE; GO SELECT next value FOR dbo.SequenceID; -- Guess the number SELECT next value FOR dbo.SequenceID; -- Clean up DROP SEQUENCE dbo.SequenceID; GO Please note that Starting value is 1, Increment value is the negative value of -1 and Minimum value is 3. Now let us first assume how this will work out. In our example of the sequence starting value is equal to 1 and decrement value is -1, this means the value should decrement from 1 to 0. However, the minimum value is 1. This means the value cannot further decrement at all. What will happen here? The natural assumption is that it should throw an error. How many of you are assuming about query will throw an ERROR? Well, you are WRONG! Do not blame yourself, it is my fault as I have told you only half of the story. Now if you have voted for error, let us continue running above code in SQL Server Management Studio. The above script will give the following output: Isn’t it interesting that instead of error out it is giving us result value 3. To understand the answer about the same, carefully observe the original syntax of creating SEQUENCE – there is a keyword CYCLE. This keyword cycles the values between the minimum and maximum value and when one of the range is exhausted it cycles the values from the other end of the cycle. As we have negative incremental value when query reaches to the minimum value or lower end it will cycle it from the maximum value. Here the maximum value is 3 so the next logical value is 3. If your business requirement is such that if sequence reaches the maximum or minimum value, it should throw an error, you should not use the keyword cycle, and it will behave as discussed. I hope, you are enjoying the puzzles as much as I am enjoying it. If you have any interesting puzzle to share, please do share with me and I will share this on blog with due credit to you. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• SQL SERVER – Identifying Column Data Type of uniqueidentifier without Querying System Tables

  - by pinaldave

  I love interesting conversations with related to SQL Server. One of my friends Madhivanan always comes up with an interesting point of conversation. Here is one of the conversation between us. I am very confident this blog post will for sure enable you with some new knowledge. Madhi: How do I know if any table has a uniqueidentifier column used in it? Pinal:  I am sure you know that you can do it through some DMV or catalogue views. Madhi: I know that but how can we do that without using DMV or catalogue views? Pinal: Hm… what can I use? Madhi: You can use table name. Pinal: Easy, just say SELECT YourUniqueIdentCol FROM Table. Madhi: Hold on, the question seems to be not clear to you – you do know the name of the column. The matter of the fact, you do not know if the table has uniqueidentifier column. Only information you have is table name. Pinal: Madhi, this seems like you are changing the question when I am close to answer. Madhi: Well, are you clear now? Let me say it again – How do I know if any table has a uniqueidentifier column and what is its value without using any DMV or System Catalogues? Only information you know is table name and you are allowed to return any kind of error if table does not have uniqueidentifier column. Pinal: Do you know the answer? Madhi: Yes. I just wanted to test your knowledge about SQL. Pinal: I will have to think. Let me accept I do not know it right away. Can you share the answer please? Madhi: I won! Here it goes! Pinal: When I have friends like you – who needs enemies? Madhi: (laughter which did not stop for a minute). CREATE TABLE t ( GuidCol UNIQUEIDENTIFIER DEFAULT newsequentialid() ROWGUIDCOL, data VARCHAR(60) ) INSERT INTO t (data) SELECT 'test' INSERT INTO t (data) SELECT 'test1' SELECT $rowguid FROM t DROP TABLE t This is indeed very interesting to me. Please note that this is not the optimal way and there will be many other ways to retrieve uniqueidentifier name and value. What I learned from this was if I am in a rush to check if the table has uniqueidentifier and I do not know the name of the same, I can use SELECT TOP (1) $rowguid and quickly know the name of the column. I can later use the same columnname in my query. Madhi did teach me this new trick. Did you know this? What are other ways to get the check uniqueidentifier column existence in a database? Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Puzzle #1 – Querying Pattern Ranges and Wild Cards

  - by Pinal Dave

  Note: Read at the end of the blog post how you can get five Joes 2 Pros Book #1 and a surprise gift. I have been blogging for almost 7 years and every other day I receive questions about Querying Pattern Ranges. The most common way to solve the problem is to use Wild Cards. However, not everyone knows how to use wild card properly. SQL Queries 2012 Joes 2 Pros Volume 1 – The SQL Queries 2012 Hands-On Tutorial for Beginners Book On Amazon | Book On Flipkart Learn SQL Server get all the five parts combo kit Kit on Amazon | Kit on Flipkart Many people know wildcards are great for finding patterns in character data. There are also some special sequences with wildcards that can give you even more power. This series from SQL Queries 2012 Joes 2 Pros® Volume 1 will show you some of these cool tricks. All supporting files are available with a free download from the www.Joes2Pros.com web site. This example is from the SQL 2012 series Volume 1 in the file SQLQueries2012Vol1Chapter2.2Setup.sql. If you need help setting up then look in the “Free Videos” section on Joes2Pros under “Getting Started” called “How to install your labs” Querying Pattern Ranges The % wildcard character represents any number of characters of any length. Let’s find all first names that end in the letter ‘A’. By using the percentage ‘%’ sign with the letter ‘A’, we achieve this goal using the code sample below: SELECT * FROM Employee WHERE FirstName LIKE '%A' To find all FirstName values beginning with the letters ‘A’ or ‘B’ we can use two predicates in our WHERE clause, by separating them with the OR statement. Finding names beginning with an ‘A’ or ‘B’ is easy and this works fine until we want a larger range of letters as in the example below for ‘A’ thru ‘K’: SELECT * FROM Employee WHERE FirstName LIKE 'A%' OR FirstName LIKE 'B%' OR FirstName LIKE 'C%' OR FirstName LIKE 'D%' OR FirstName LIKE 'E%' OR FirstName LIKE 'F%' OR FirstName LIKE 'G%' OR FirstName LIKE 'H%' OR FirstName LIKE 'I%' OR FirstName LIKE 'J%' OR FirstName LIKE 'K%' The previous query does find FirstName values beginning with the letters ‘A’ thru ‘K’. However, when a query requires a large range of letters, the LIKE operator has an even better option. Since the first letter of the FirstName field can be ‘A’, ‘B’, ‘C’, ‘D’, ‘E’, ‘F’, ‘G’, ‘H’, ‘I’, ‘J’ or ‘K’, simply list all these choices inside a set of square brackets followed by the ‘%’ wildcard, as in the example below: SELECT * FROM Employee WHERE FirstName LIKE '[ABCDEFGHIJK]%' A more elegant example of this technique recognizes that all these letters are in a continuous range, so we really only need to list the first and last letter of the range inside the square brackets, followed by the ‘%’ wildcard allowing for any number of characters after the first letter in the range. Note: A predicate that uses a range will not work with the ‘=’ operator (equals sign). It will neither raise an error, nor produce a result set. --Bad query (will not error or return any records) SELECT * FROM Employee WHERE FirstName = '[A-K]%' Question: You want to find all first names that start with the letters A-M in your Customer table and end with the letter Z. Which SQL code would you use? a. SELECT * FROM Customer WHERE FirstName LIKE 'm%z' b. SELECT * FROM Customer WHERE FirstName LIKE 'a-m%z' c. SELECT * FROM Customer WHERE FirstName LIKE 'a-m%z' d. SELECT * FROM Customer WHERE FirstName LIKE '[a-m]%z' e. SELECT * FROM Customer WHERE FirstName LIKE '[a-m]z%' f. SELECT * FROM Customer WHERE FirstName LIKE '[a-m]%z' g. SELECT * FROM Customer WHERE FirstName LIKE '[a-m]z%' Contest Leave a valid answer before June 18, 2013 in the comment section. 5 winners will be selected from all the valid answers and will receive Joes 2 Pros Book #1. 1 Lucky person will get a surprise gift from Joes 2 Pros. The contest is open for all the countries where Amazon ships the book (USA, UK, Canada, India and many others). Special Note: Read all the options before you provide valid answer as there is a small trick hidden in answers. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – #TechEdIn – Presenting Tomorrow on Speed Up! – Parallel Processes and Unparalleled Performance at TechEd India 2012

  - by pinaldave

  Performance tuning is always a very hot topic when it is about SQL Server. SQL Server Performance Tuning is a very challenging subject that requires expertise in Database Administration and Database Development. I always have enjoyed talking about SQL Server Performance tuning subject. However, in India, it’s actually the very first time someone is presenting on this interesting subject, so this time I had the biggest challenge to present this session. Frequently enough, we get these two kind of questions: How to turn off parallelism as it is reducing performance? How to turn on parallelism as I want more performance? The reality is that not everyone knows what exactly is needed by their system. In this session, I have attempted to answer this very question. I’ve decided to provide a balanced view but stay away from theory, which leads us to say “It depends”. The session will have a clear message about this towards its end. Deck Details Slides: 45+ Demos: 7+ Bonus Quiz: 5 Images: 10+ Session delivery time: 52 Mins + 8 Mins of Q & A I have presented this session a couple of times to my friends and so far have received good feedback. Oftentimes, when people hear that I am going to present 45 slides, they all say it is too much to cover. However, when I am done with the session the usual reaction is that I truly gave justice to those slides. Action Item Here are a few of the action items for all of those who are going to attend this session: If you want to attend the session, just come early. There’s a good chance that you may not get a seat because right before me, there is a session from SQL Guru Vinod Kumar. He performs a powerful delivery of million concepts in just a little time. Quiz. I will be asking few questions during the session as well as before the session starts. If you get the correct answer, I will give unique learning material for you. You may not want to miss this learning opportunity at any cosst. Session Details Title: Speed Up! – Parallel Processes and Unparalleled Performance (Add to Calendar) Abstract: “More CPU, More Performance” – A  very common understanding is that usage of multiple CPUs can improve the performance of the query. To get a maximum performance out of any query, one has to master various aspects of the parallel processes. In this deep-dive session, we will explore this complex subject with a very simple interactive demo. Attendees will walk away with proper understanding of CX_PACKET wait types, MAXDOP, parallelism threshold and various other concepts. Date and Time: March 23, 2012, 12:15 to 13:15 Location: Hotel Lalit Ashok - Kumara Krupa High Grounds, Bengaluru – 560001, Karnataka, India. Add to Calendar Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Interview Questions and Answers, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• SQL SERVER – Renaming Index – Index Naming Conventions

  - by pinaldave

  If you are regular reader of this blog, you must be aware of that there are two kinds of blog posts 1) I share what I learn recently 2) I share what I learn and request your participation. Today’s blog post is where I need your opinion to make this blog post a good reference for future. Background Story Recently I came across system where users have changed the name of the few of the table to match their new standard naming convention. The name of the table should be self explanatory and they should have explain their purpose without either opening it or reading documentations. Well, not every time this is possible but again this should be the goal of any database modeler. Well, I no way encourage the name of the tables to be too long like ‘ContainsDetailsofNewInvoices’. May be the name of the table should be ‘Invoices’ and table should contain a column with New/Processed bit filed to indicate if the invoice is processed or not (if necessary). Coming back to original story, the database had several tables of which the name were changed. Story Continues… To continue the story let me take simple example. There was a table with the name  ’ReceivedInvoices’, it was changed to new name as ‘TblInvoices’. As per their new naming standard they had to prefix every talbe with the words ‘Tbl’ and prefix every view with the letters ‘Vw’. Personally I do not see any need of the prefix but again, that issue is not here to discuss.  Now after changing the name of the table they faced very interesting situation. They had few indexes on the table which had name of the table. Let us take an example. Old Name of Table: ReceivedInvoice Old Name of Index: Index_ReceivedInvoice1 Here is the new names New Name of Table: TblInvoices New Name of Index: ??? Well, their dilemma was what should be the new naming convention of the Indexes. Here is a quick proposal of the Index naming convention. Do let me know your opinion. If Index is Primary Clustered Index: PK_TableName If Index is  Non-clustered Index: IX_TableName_ColumnName1_ColumnName2… If Index is Unique Non-clustered Index: UX_TableName_ColumnName1_ColumnName2… If Index is Columnstore Non-clustered Index: CL_TableName Here ColumnName is the column on which index is created. As there can be only one Primary Key Index and Columnstore Index per table, they do not require ColumnName in the name of the index. The purpose of this new naming convention is to increase readability. When any user come across this index, without opening their properties or definition, user can will know the details of the index. T-SQL script to Rename Indexes Here is quick T-SQL script to rename Indexes EXEC sp_rename N'SchemaName.TableName.IndexName', N'New_IndexName', N'INDEX'; GO Your Contribute Please Well, the organization has already defined above four guidelines, personally I follow very similar guidelines too. I have seen many variations like adding prefixes CL for Clustered Index and NCL for Non-clustered Index. I have often seen many not using UX prefix for Unique Index but rather use generic IX prefix only. Now do you think if they have missed anything in the coding standard. Is NCI and CI prefixed required to additionally describe the index names. I have once received suggestion to even add fill factor in the index name – which I do not recommend at all. What do you think should be ideal name of the index, so it explains all the most important properties? Additionally, you are welcome to vote if you believe changing the name of index is just waste of time and energy.  Note: The purpose of the blog post is to encourage all to participate with their ideas. I will write follow up blog posts in future compiling all the suggestions. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Asynchronous Update and Timestamp – Check if Row Values are Changed Since Last Retrieve

  - by pinaldave

  Here is the question received just this morning. “Pinal, Our application is much different than other application you might have come across. In simple words, I would like to call it Asynchronous Updated Application. We need your quick opinion about one of the situation which we are facing. From business side: We have bidding system (similar to eBay but not exactly) and where multiple parties bid on one item, during the last few minutes of bidding many parties try to bid at the same time with the same price. When they hit submit, we would like to check if the original data which they retrieved is changed or not. If the original data which they have retrieved is the same, we will accept their new proposed price. If original data are changed, they will have to resubmit the data with new price. From technical side: We have a row which we retrieve in our application. Multiple users are retrieving the same row. Some of the users will update the value of the row and submit. However, only the very first user should be allowed to update the row and remaining all the users will have to re-fetch the row and updated it once again. We do not want to lock any record as that will create other problems. Do you have any solution for this kind of situation?” Fantastic Question. I believe there is good chance that we can use timestamp datatype in this kind of application. Before we continue let us see following simple example. USE tempdb GO CREATE TABLE SampleTable (ID INT, Col1 VARCHAR(100), TimeStampCol TIMESTAMP) GO INSERT INTO SampleTable (ID, Col1) VALUES (1, 'FirstVal') GO SELECT ID, Col1, TimeStampCol FROM SampleTable st GO UPDATE SampleTable SET Col1 = 'NextValue' GO SELECT ID, Col1, TimeStampCol FROM SampleTable st GO DROP TABLE SampleTable GO Now let us see the resultset. Here is the simple explanation of the scenario. We created a table with simple column with TIMESTAMP datatype. When we inserted a very first value the timestamp was generated. When we updated any value in that row, the timestamp was updated with the new value. Every single time when we update any value in the row, it will generate new timestamp value. Now let us apply this in an original question’s scenario. In that case multiple users are retrieving the same row. Everybody will have the same now same TimeStamp with them. Before any user update any value they should once again retrieve the timestamp from the table and compare with the timestamp they have with them. If both of the timestamp have the same value – the original row has not been updated and we can safely update the row with the new value. After initial update, now the row will contain a new timestamp. Any subsequent update to the same row should also go to the same process of checking the value of the timestamp they have in their memory. In this case, the timestamp from memory will be different from the timestamp in the row. This indicates that row in the table has changed and new updates should not be allowed. I believe timestamp can be very very useful in this kind of scenario. Is there any better alternative? Please leave a comment with the suggestion and I will post on the blog with due credit. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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