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• SQL SERVER – Relationship with Parallelism with Locks and Query Wait – Question for You

  - by Pinal Dave

  Today, I have one very simple question based on following image. A full disclaimer is that I have no idea why it is like that. I tried to reach out to few of my friends who know a lot about SQL Server but no one has any answer. Here is the question: If you go to server properties and click on Advanced you will see the following screen. Under the Parallelism section if you noticed there are four options: Cost Threshold for Parallelism Locks Max Degree of Parallelism Query Wait I can clearly understand why Cost Threshold for Parallelism and Max Degree of Parallelism belongs to Parallelism but I am not sure why we have two other options Locks and Query Wait belongs to Parallelism section. I can see that the options are ordered alphabetically but I do not understand the reason for locks and query wait to list under Parallelism. Here is the question for you – Why Locks and Query Wait options are listed under Parallelism section in SQL Server Advanced Properties? Please leave a comment with your explanation. I will publish valid answers on this blog with due credit. Reference: Pinal Dave (http://blog.sqlauthority.com)   Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – 2012 – List All The Column With Specific Data Types in Database

  - by pinaldave

  5 years ago I wrote script SQL SERVER – 2005 – List All The Column With Specific Data Types, when I read it again, it is very much relevant and I liked it. This is one of the script which every developer would like to keep it handy. I have upgraded the script bit more. I have included few additional information which I believe I should have added from the beginning. It is difficult to visualize the final script when we are writing it first time. I use every script which I write on this blog, the matter of the fact, I write only those scripts here which I was using at that time. It is quite possible that as time passes by my needs are changing and I change my script. Here is the updated script of this subject. If there are any user data types, it will list the same as well. SELECT s.name AS 'schema', ts.name AS TableName, c.name AS column_name, c.column_id, SCHEMA_NAME(t.schema_id) AS DatatypeSchema, t.name AS Datatypename ,t.is_user_defined, t.is_assembly_type ,c.is_nullable, c.max_length, c.PRECISION, c.scale FROM sys.columns AS c INNER JOIN sys.types AS t ON c.user_type_id=t.user_type_id INNER JOIN sys.tables ts ON ts.OBJECT_ID = c.OBJECT_ID INNER JOIN sys.schemas s ON s.schema_id = t.schema_id ORDER BY s.name, ts.name, c.column_id I would be very interested to see your script which lists all the columns of the database with data types. If I am missing something in my script, I will modify it based on your comment. This way this page will be a good bookmark for the future for all of us. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Server, SQL System Table, SQL Tips and Tricks, T SQL, Technology

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• Big Data – Final Wrap and What Next – Day 21 of 21

  - by Pinal Dave

  In yesterday’s blog post we explored various resources related to learning Big Data and in this blog post we will wrap up this 21 day series on Big Data. I have been exploring various terms and technology related to Big Data this entire month. It was indeed fun to write about Big Data in 21 days but the subject of Big Data is much bigger and larger than someone can cover it in 21 days. My first goal was to write about the basics and I think we have got that one covered pretty well. During this 21 days I have received many questions and answers related to Big Data. I have covered a few of the questions in this series and a few more I will be covering in the next coming months. Now after understanding Big Data basics. I am personally going to do a list of the things next. I thought I will share the same with you as this will give you a good idea how to continue the journey of the Big Data. Build a schedule to read various Apache documentations Watch all Pluralsight Courses Explore HortonWorks Sandbox Start building presentation about Big Data – this is a great way to learn something new Present in User Groups Meetings on Big Data Topics Write more blog posts about Big Data I am going to continue learning about Big Data – I want you to continue learning Big Data. Please leave a comment how you are going to continue learning about Big Data. I will publish all the informative comments on this blog with due credit. I want to end this series with the infographic by UMUC. 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

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• SQL SERVER – 2014 Announced and SQL Server 2014 Datasheet

  - by Pinal Dave

  Earlier this week Microsoft has announced SQL Server 2014. The release date of Trial of SQL Server to be believed later this year. Here are few of the improvements which I was looking forward are there in this release. Please note this is not the exhaustive list of the features of SQL Server 2014. This is the a quick note on the features which I was looking forward and now will be available in this release. Always On supports now 8 secondaries instead of 4 Online Indexing at partition level – this is a good thing as now index rebuilding can be done at a partition level Statistics at the partition level – this will be a huge improvement in performance In-Memory OLTP works by providing in-application memory storage for the most often used tables in SQL Server. (Read More Here) Columnstore Index can be updated – I just can’t wait for this feature (Columnstore Index) Resource Governor can control IO along with CPU and Memory Increase performance by extending SQL Server in-memory buffer pool to SSDs Backup to Azure Storage You can additionally download SQL Server 2014 Datasheet from here. Which is your favorite new feature of SQL Server 2014? 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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• MySQL – How to Write Loop in MySQL

  - by Pinal Dave

  Since, I have written courses on MySQL, I quite often get emails about MySQL courses. Here is the question, which I have received quite often. “How do I loop queries in MySQL?” Well, currently MySQL does not allow to write loops with the help of ad-hoc SQL. You have to write stored procedure (routine) for the same. Here is the example, how we can create a procedure in MySQL which will look over the code. In this example I have used SELECT 1 statement and looped over it. In reality you can put there any code and loop over it. This procedure accepts one parameter which is the number of the count the loop will iterate itself. delimiter // CREATE PROCEDURE doiterate(p1 INT) BEGIN label1: LOOP SET p1 = p1 - 1; IF p1 > 0 THEN SELECT 1; ITERATE label1; END IF; LEAVE label1; END LOOP label1; END// delimiter ; CALL doiterate(100); You can also use WHILE to loop as well, we will see that in future blog posts. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: MySQL, PostADay, SQL, SQL Authority, SQL Query, SQL Tips and Tricks, T SQL

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• SQL SERVER – ORDER BY ColumnName vs ORDER BY ColumnNumber

  - by pinaldave

  I strongly favor ORDER BY ColumnName. I read one of the blog post where blogger compared the performance of the two SELECT statement and come to conclusion that ColumnNumber has no harm to use it. Let us understand the point made by first that there is no performance difference. Run following two scripts together: USE AdventureWorks GO -- ColumnName (Recommended) SELECT * FROM HumanResources.Department ORDER BY GroupName, Name GO -- ColumnNumber (Strongly Not Recommended) SELECT * FROM HumanResources.Department ORDER BY 3,2 GO If you look at the result and see the execution plan you will see that both of the query will take the same amount of the time. However, this was not the point of this blog post. It is not good enough to stop here. We need to understand the advantages and disadvantages of both the methods. Case 1: When Not Using * and Columns are Re-ordered USE AdventureWorks GO -- ColumnName (Recommended) SELECT GroupName, Name, ModifiedDate, DepartmentID FROM HumanResources.Department ORDER BY GroupName, Name GO -- ColumnNumber (Strongly Not Recommended) SELECT GroupName, Name, ModifiedDate, DepartmentID FROM HumanResources.Department ORDER BY 3,2 GO Case 2: When someone changes the schema of the table affecting column order I will let you recreate the example for the same. If your development server where your schema is different than the production server, if you use ColumnNumber, you will get different results on the production server. Summary: When you develop the query it may not be issue but as time passes by and new columns are added to the SELECT statement or original table is re-ordered if you have used ColumnNumber it may possible that your query will start giving you unexpected results and incorrect ORDER BY. One should note that the usage of ORDER BY ColumnName vs ORDER BY ColumnNumber should not be done based on performance but usability and scalability. It is always recommended to use proper ORDER BY clause with ColumnName to avoid any confusion. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – First Month as DBA Trainee – Disasters and Recovery

  - by pinaldave

  This blog post is written in response to the T-SQL Tuesday hosted by Allen Kinsel. He has selected very interesting subject for T-SQL Tuesday – Disaster and Recovery. This subject took me in past – my past. There were various things, I had done or proposed when I started very first month as a DBA trainee. I was tagged along with very senior DBA in my organization who always protected me or correct my mistake. He was great guy and totally understand the young mind of over-enthusiastic Trainee DBA. I respect him very much. Here are few things which I had learned in my very first month (not necessarily I have practices them on production). Never compress (zip) native backup using any tools, when disaster happen sometime the extra time to un-compress the database can be too long and not acceptable for business SLA Do not truncate logs After restoring full database backup – only restore latest differential back, no need to restore all the backup Always write WHERE condition when deleting and updating Sr. DBA always advised me – always keep your résumé ready and car ready – you never know when you can not recover disaster! Well for sure it was a joke. Today’s T-SQL Tuesday remind me of my very first month as DBA trainee. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, Best Practices, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL – Difference Between INNER JOIN and JOIN

  - by Pinal Dave

  Here is the follow up question to my earlier question SQL – Difference between != and Operator <> used for NOT EQUAL TO Operation. There was a pretty good discussion about this subject earlier and lots of people participated with their opinion. Though the answer was very simple but the conversation was indeed delightful and was indeed very informative. In this blog post I have another following up question to all of you. What is the difference between INNER JOIN and JOIN? If you are working with database you will find developers use above both the kinds of the joins in their SQL Queries. Here is the quick example of the same. Query using INNER JOIN SELECT * FROM Table1 INNER JOIN  Table2 ON Table1.Col1 = Table2.Col1 Query using JOIN SELECT * FROM Table1 JOIN  Table2 ON Table1.Col1 = Table2.Col1 The question is what is the difference between above two syntax. Here is the answer – They are equal to each other. There is absolutely no difference between them. They are equal in performance as well as implementation. JOIN is actually shorter version of INNER JOIN. Personally I prefer to write INNER JOIN because it is much cleaner to read and it avoids any confusion if there is related to JOIN. For example if users had written INNER JOIN instead of JOIN there would have been no confusion in mind and hence there was no need to have original question. Here is the question back to you - Which one of the following syntax do you use when you are inner joining two tables – INNER JOIN or JOIN? and Why? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Joins, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Technical Reference Guides for Designing Mission-Critical Solutions – A Must Read

  - by pinaldave

  Yesterday I was reading architecture reference material helping my friend who was looking for material in this respect. While working together we were searching twitter, facebook and search engines to find relevant material.While searching online we end up on very interactive reference point. Once I send the same to him, he replied he may not need anything more after referencing this material. The best part of this article was it gives access to various aspect of the technology of the image map. Here is the abstract of the original article from the site: The Technical Reference Guides for Designing Mission-Critical Solutions provide planning and architecture guidance for various mission-critical workloads deployed by users. These guides reflect the knowledge gained by Microsoft while working with customers on mission-critical deployments. Each guide provides not only the key technical concepts and information helpful for design, but also “lessons learned,” best practices, and references to customer case studies. Once you click on any of the desired topic, you will see further detailed image map of the selected topic. Personally once I ended up on this site, I was there for more than 2 hours clicking through various links. Click on image to see larger image Read more here: Technical Reference Guides for Designing Mission-Critical Solutions Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL White Papers, T SQL, Technology

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• SQL SERVER – Weekly Series – Memory Lane – #037

  - by Pinal Dave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Convert Text to Numbers (Integer) – CAST and CONVERT If table column is VARCHAR and has all the numeric values in it, it can be retrieved as Integer using CAST or CONVERT function. List All Stored Procedure Modified in Last N Days If SQL Server suddenly start behaving in un-expectable behavior and if stored procedure were changed recently, following script can be used to check recently modified stored procedure. If a stored procedure was created but never modified afterwards modified date and create a date for that stored procedure are same. Count Duplicate Records – Rows Validate Field For DATE datatype using function ISDATE() We always checked DATETIME field for incorrect data type. One of the user input date as 30/2/2007. The date was sucessfully inserted in the temp table but while inserting from temp table to final table it crashed with error. We had now task to validate incorrect date value before we insert in final table. Jr. Developer asked me how can he do that? We check for incorrect data type (varchar, int, NULL) but this is incorrect date value. Regular expression works fine with them because of mm/dd/yyyy format. 2008 Find Space Used For Any Particular Table It is very simple to find out the space used by any table in the database. Two Convenient Features Inline Assignment – Inline Operations Here is the script which does both – Inline Assignment and Inline Operation DECLARE @idx INT = 0 SET @idx+=1 SELECT @idx Introduction to SPARSE Columns SPARSE column are better at managing NULL and ZERO values in SQL Server. It does not take any space in database at all. If column is created with SPARSE clause with it and it contains ZERO or NULL it will be take lesser space then regular column (without SPARSE clause). SP_CONFIGURE – Displays or Changes Global Configuration Settings If advanced settings are not enabled at configuration level SQL Server will not let user change the advanced features on server. Authorized user can turn on or turn off advance settings. 2009 Standby Servers and Types of Standby Servers Standby Server is a type of server that can be brought online in a situation when Primary Server goes offline and application needs continuous (high) availability of the server. There is always a need to set up a mechanism where data and objects from primary server are moved to secondary (standby) server. BLOB – Pointer to Image, Image in Database, FILESTREAM Storage When it comes to storing images in database there are two common methods. I had previously blogged about the same subject on my visit to Toronto. With SQL Server 2008, we have a new method of FILESTREAM storage. However, the answer on when to use FILESTREAM and when to use other methods is still vague in community. 2010 Upper Case Shortcut SQL Server Management Studio I select the word and hit CTRL+SHIFT+U and it SSMS immediately changes the case of the selected word. Similar way if one want to convert cases to lower case, another short cut CTRL+SHIFT+L is also available. The Self Join – Inner Join and Outer Join Self Join has always been a noteworthy case. It is interesting to ask questions about self join in a room full of developers. I often ask – if there are three kinds of joins, i.e.- Inner Join, Outer Join and Cross Join; what type of join is Self Join? The usual answer is that it is an Inner Join. However, the reality is very different. Parallelism – Row per Processor – Row per Thread – Thread 0  If you look carefully in the Properties window or XML Plan, there is “Thread 0?. What does this “Thread 0” indicate? Well find out from the blog post. How do I Learn and How do I Teach The blog post has raised three very interesting questions. How do you learn? How do you teach? What are you learning or teaching? Let me try to answer the same. 2011 SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 7 of 31 What are Different Types of Locks? What are Pessimistic Lock and Optimistic Lock? When is the use of UPDATE_STATISTICS command? What is the Difference between a HAVING clause and a WHERE clause? What is Connection Pooling and why it is Used? What are the Properties and Different Types of Sub-Queries? What are the Authentication Modes in SQL Server? How can it be Changed? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 8 of 31 Which Command using Query Analyzer will give you the Version of SQL Server and Operating System? What is an SQL Server Agent? Can a Stored Procedure call itself or a Recursive Stored Procedure? How many levels of SP nesting is possible? What is Log Shipping? Name 3 ways to get an Accurate Count of the Number of Records in a Table? What does it mean to have QUOTED_IDENTIFIER ON? What are the Implications of having it OFF? What is the Difference between a Local and a Global Temporary Table? What is the STUFF Function and How Does it Differ from the REPLACE Function? What is PRIMARY KEY? What is UNIQUE KEY Constraint? What is FOREIGN KEY? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 9 of 31 What is CHECK Constraint? What is NOT NULL Constraint? What is the difference between UNION and UNION ALL? What is B-Tree? How to get @@ERROR and @@ROWCOUNT at the Same Time? What is a Scheduled Job or What is a Scheduled Task? What are the Advantages of Using Stored Procedures? What is a Table Called, if it has neither Cluster nor Non-cluster Index? What is it Used for? Can SQL Servers Linked to other Servers like Oracle? What is BCP? When is it Used? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 10 of 31 What Command do we Use to Rename a db, a Table and a Column? What are sp_configure Commands and SET Commands? How to Implement One-to-One, One-to-Many and Many-to-Many Relationships while Designing Tables? What is Difference between Commit and Rollback when Used in Transactions? What is an Execution Plan? When would you Use it? How would you View the Execution Plan? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 11 of 31 What is Difference between Table Aliases and Column Aliases? Do they Affect Performance? What is the difference between CHAR and VARCHAR Datatypes? What is the Difference between VARCHAR and VARCHAR(MAX) Datatypes? What is the Difference between VARCHAR and NVARCHAR datatypes? Which are the Important Points to Note when Multilanguage Data is Stored in a Table? How to Optimize Stored Procedure Optimization? What is SQL Injection? How to Protect Against SQL Injection Attack? How to Find Out the List Schema Name and Table Name for the Database? What is CHECKPOINT Process in the SQL Server? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 12 of 31 How does Using a Separate Hard Drive for Several Database Objects Improves Performance Right Away? How to Find the List of Fixed Hard Drive and Free Space on Server? Why can there be only one Clustered Index and not more than one? What is Difference between Line Feed (\n) and Carriage Return (\r)? Is It Possible to have Clustered Index on Separate Drive From Original Table Location? What is a Hint? How to Delete Duplicate Rows? Why the Trigger Fires Multiple Times in Single Login? 2012 CTRL+SHIFT+] Shortcut to Select Code Between Two Parenthesis Shortcut key is CTRL+SHIFT+]. This key can be very useful when dealing with multiple subqueries, CTE or query with multiple parentheses. When exercised this shortcut key it selects T-SQL code between two parentheses. Monday Morning Puzzle – Query Returns Results Sometimes but Not Always I am beginner with SQL Server. I have one query, it sometime returns a result and sometime it does not return me the result. Where should I start looking for a solution and what kind of information I should send to you so you can help me with solving. I have no clue, please guide me. Remove Debug Button in SSMS – SQL in Sixty Seconds #020 – Video Effect of Case Sensitive Collation on Resultset Collation is a very interesting concept but I quite often see it is heavily neglected. I have seen developer and DBA looking for a workaround to fix collation error rather than understanding if the side effect of the workaround. Switch Between Two Parenthesis using Shortcut CTRL+] Earlier this week I wrote a blog post about CTRL+SHIFT+] Shortcut to Select Code Between Two Parenthesis, I received quite a lot of positive feedback from readers. If you are a regular reader of the blog post, you must be aware that I appreciate the learning shared by readers. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – New Look for CodePlexProject – Hosting for Open Source Software

  - by pinaldave

  Codeplex is my favorite site. CodePlex is Microsoft’s free open source project hosting site. You can create projects to share with the world, collaborate with others on their projects, and download open source software. It is great place to find so many open source project available to explore. All the softwares are free and open source. I often go there at intervals to check what is new in SQL Server field as well on other technologies. Yesterday when I visited it, I had nice surprise as it has total makeover and looks very decent as well elegant at the same time. I have noticed that when I talk about Codeplex is user community, not everybody knows about it. The quickest way I explain what is codeplex is that I start naming few of the projects which are available there and suddenly I start noticing a few hands going up knowing the projects. This is indirect way to prove that many of us know CodePlex usability but do not pay special attention to what it is actually. Let me name a few popular projects of the CodePlex here. SQL Server Sample Database [link] Image Resizer for Windows [link] Ajax Control Toolkit [link] Skype Voice Changer [link] Silverlight Toolkit [link] Windows 7 USB/DBD Download Tool [link] Orchard Project [link] There are very interesting SQL Server projects available on Codeplex as well. I am listing few of them here for reference in listed in no particular order. SQL Server Sample Database [link] SQL Server Compact ToolBox [link] Microsoft Drivers for PHP for SQL Server [link] Internals Viewer for SQL Server [link] SQL Server Spatial Tooks [link] SQL Monitor – managing sql server performance [link] SQL Server 2008 Extended Events SSMS Addin [link] How many of above mentioned project have you come across earlier? Leave a comment it will be interesting to know what our community is familiar with. 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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• SQL SERVER – Answer – Value of Identity Column after TRUNCATE command

  - by pinaldave

  Earlier I had one conversation with reader where I almost got a headache. I suggest all of you to read it before continuing this blog post SQL SERVER – Reseting Identity Values for All Tables. I believed that he faced this situation because he did not understand the difference between SQL SERVER – DELETE, TRUNCATE and RESEED Identity. I wrote a follow up blog post explaining the difference between them. I asked a small question in the second blog post and I received many interesting comments. Let us go over the question and its answer here one more time. Here is the scenario to set up the puzzle. Create Table with Seed Identity = 11 Insert Value and Check Seed (it will be 11) Reseed it to 1 Insert Value and Check Seed (it will be 2) TRUNCATE Table Insert Value and Check Seed (it will be 11) Let us see the T-SQL Script for the same. USE [TempDB] GO -- Create Table CREATE TABLE [dbo].[TestTable]( [ID] [int] IDENTITY(11,1) NOT NULL, [var] [nchar](10) NULL ) ON [PRIMARY] GO -- Build sample data INSERT INTO [TestTable] VALUES ('val') GO -- Select Data SELECT * FROM [TestTable] GO -- Reseed to 1 DBCC CHECKIDENT ('TestTable', RESEED, 1) GO -- Build sample data INSERT INTO [TestTable] VALUES ('val') GO -- Select Data SELECT * FROM [TestTable] GO -- Truncate table TRUNCATE TABLE [TestTable] GO -- Build sample data INSERT INTO [TestTable] VALUES ('val') GO -- Select Data SELECT * FROM [TestTable] GO -- Question for you Here -- Clean up DROP TABLE [TestTable] GO Now let us see the output of three of the select statements. 1) First Select after create table 2) Second Select after reseed table 3) Third Select after truncate table The reason is simple: If the table contains an identity column, the counter for that column is reset to the seed value defined for the column. Reference: Pinal Dave (http://blog.sqlauthority.com)       Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• SQL SERVER – A Cool Trick – Restoring the Default SQL Server Management Studio – SSMS

  - by pinaldave

  “I do not know where my windows went!” “I just closed my object explorer and now I cannot find it.” “How do I get my original windows layout back in SQL Server Management Studio?” “How do I get the window which was there in left side back again?” Since last 2-3 years, every single day I receive more than 5 emails on SSMS and its layout. For the beginners it is very common to get confused when they attempt to change SQL Server Management Studio’s windows layout. They often change the layout and are not able to get the original layout back. Often people do not change the layout whole of their life, leading to uncomfortable feeling when they go to another’s computer where the windows are differently placed. Today’s blog post is dedicated all the beginners in SQL Server. It is extremely simple to reset the SSMS layout to default layout. The default layout involves 2 major things 1) Object Explorer on left side 2) Query Windows on right side (80% screen estate). Personally I am so used to this as well that if there is any other changes in the same, I do not enjoy working on the environment. Well, the solution to rest the SSMS layout is very simple. One can do it in split seconds.  To restore the default configuration, on the Window menu, click Reset Window Layout. Have you ever used this feature? Do you feel uncomfortable when SSMS layout is not in default state? How do you address this situation? 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 – Finding Size of a Columnstore Index Using DMVs

  - by pinaldave

  Columnstore Index is one of my favorite enhancement in SQL Server 2012. A columnstore index stores each column in a separate set of disk pages, rather than storing multiple rows per page as data traditionally has been stored. In case of the row store indexes multiple pages will contain multiple rows of the columns spanning across multiple pages. Whereas in case of column store indexes multiple pages will contain (multiple) single columns.  Columnstore Indexes are compressed by default and occupies much lesser space than regular row store index by default. One of the very common question I often see is need of the list of columnstore index along with their size and corresponding table name. I quickly re-wrote a script using DMVs sys.indexes and sys.dm_db_partition_stats. This script gives the size of the columnstore index on disk only. I am sure there will be advanced script to retrieve details related to components associated with the columnstore index. However, I believe following script is sufficient to start getting an idea of columnstore index size.  SELECT OBJECT_SCHEMA_NAME(i.OBJECT_ID) SchemaName, OBJECT_NAME(i.OBJECT_ID ) TableName, i.name IndexName, SUM(s.used_page_count) / 128.0 IndexSizeinMB FROM sys.indexes AS i INNER JOIN sys.dm_db_partition_stats AS S ON i.OBJECT_ID = S.OBJECT_ID AND I.index_id = S.index_id WHERE  i.type_desc = 'NONCLUSTERED COLUMNSTORE' GROUP BY i.OBJECT_ID, i.name Here is my introductory article written on SQL Server Fundamentals of Columnstore Index. Create a sample columnstore index based on the script described in the earlier article. It will give the following results. Please feel free to suggest improvement to script so I can further modify it to accommodate enhancements. 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 Tagged: ColumnStore Index

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• SQL SERVER – Weekly Series – Memory Lane – #007

  - by pinaldave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2006 Find Stored Procedure Related to Table in Database – Search in All Stored Procedure In 2006 I wrote a small script which will help user  find all the Stored Procedures (SP) which are related to one or more specific tables. This was quite a popular script however, in SQL Server 2012 the same can be achieved using new DMV sys.sql-expression_dependencies. I recently blogged about it over Find Referenced or Referencing Object in SQL Server using sys.sql_expression_dependencies. 2007 SQL SERVER – Versions, CodeNames, Year of Release 1993 – SQL Server 4.21 for Windows NT 1995 – SQL Server 6.0, codenamed SQL95 1996 – SQL Server 6.5, codenamed Hydra 1999 – SQL Server 7.0, codenamed Sphinx 1999 – SQL Server 7.0 OLAP, codenamed Plato 2000 – SQL Server 2000 32-bit, codenamed Shiloh (version 8.0) 2003 – SQL Server 2000 64-bit, codenamed Liberty 2005 – SQL Server 2005, codenamed Yukon (version 9.0) 2008 – SQL Server 2008, codenamed Katmai (version 10.0) 2011 – SQL Server 2008, codenamed Denali (version 11.0) Search String in Stored Procedure Searching sting in the stored procedure is one of the most frequent task developer do. They might be searching for a table, view or any other details. I have written a script to do the same in SQL Server 2000 and SQL Server 2005. This is worth bookmarking blog post. There is an alternative way to do the same as well here is the example. 2008 SQL SERVER – Refresh Database Using T-SQL NO! Some of the questions have a single answer NO! You may want to read the question in the original blog post. I had a great time saying No! SQL SERVER – Delete Backup History – Cleanup Backup History SQL Server stores history of all the taken backup forever. History of all the backup is stored in the msdb database. Many times older history is no more required. Following Stored Procedure can be executed with a parameter which takes days of history to keep. In the following example 30 is passed to keep a history of month. 2009 Stored Procedure are Compiled on First Run – SP taking Longer to Run First Time Is stored procedure pre-compiled? Why the Stored Procedure takes a long time to run for the first time?  This is a very common questions often discussed by developers and DBAs. There is an absolutely definite answer but the question has been discussed forever. There is a misconception that stored procedures are pre-compiled. They are not pre-compiled, but compiled only during the first run. For every subsequent runs, it is for sure pre-compiled. Read the entire article for example and demonstration. Removing Key Lookup – Seek Predicate – Predicate – An Interesting Observation Related to Datatypes This is one of the most important performance tuning lesson on my blog. I suggest this weekend you spend time reading them and let me know what you think about the concepts which I have demonstrated in the four part series. Part 1 | Part 2 | Part 3 | Part 4 Seek Predicate is the operation that describes the b-tree portion of the Seek. Predicate is the operation that describes the additional filter using non-key columns. Based on the description, it is very clear that Seek Predicate is better than Predicate as it searches indexes whereas in Predicate, the search is on non-key columns – which implies that the search is on the data in page files itself. Policy Based Management – Create, Evaluate and Fix Policies This article will cover the most spectacular feature of SQL Server – Policy-based management and how the configuration of SQL Server with policy-based management architecture can make a powerful difference. Policy based management is loaded with several advantages. It can help you implement various policies for reliable configuration of the system. It also provides additional administration assistance to DBAs and helps them effortlessly manage various tasks of SQL Server across the enterprise. 2010 Recycle Error Log – Create New Log file without Server Restart Once I observed a DBA to restaring the SQL Server when he needed new error log file. This was funny and sad both at the same time. There is no need to restart the server to create a new log file or recycle the log file. You can run sp_cycle_errorlog and achieve the same result. Get Database Backup History for a Single Database Simple but effective script! Reducing CXPACKET Wait Stats for High Transactional Database The subject is very complex and I have done my best to simplify the concept. In simpler words, when a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. Threads which came first have to wait for the slower thread to finish. The Wait by a specific completed thread is called CXPACKET Wait Stat. Information Related to DATETIME and DATETIME2 There are quite a lot of confusion with DATETIME and DATETIME2. DATETIME2 is also one of the underutilized datatype of SQL Server.  In this blog post I have written a follow up of the my earlier datetime series where I clarify a few of the concepts related to datetime. Difference Between GETDATE and SYSDATETIME Difference Between DATETIME and DATETIME2 – WITH GETDATE Difference Between DATETIME and DATETIME2 2011 Introduction to CUME_DIST – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical function CUME_DIST(). This function provides cumulative distribution value. 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. Introduction to FIRST _VALUE and LAST_VALUE – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical functions FIRST_VALUE() and LAST_VALUE(). This function returns first and last value from the list. It will be very difficult to explain this in words so I’d like to attempt to explain its function through a brief example. Instead of creating a new table, I will be using the AdventureWorks sample database as most developers use that for experiment purposes. OVER clause with FIRST _VALUE and LAST_VALUE – Analytic Functions Introduced in SQL Server 2012 – ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING “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.” Puzzle – Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY 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. Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012 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. A Real Story of Book Getting ‘Out of Stock’ to A 25% Discount Story Available Our book was out of stock in 48 hours of it was arrived in stock! We got call from the online store with a request for more copies within 12 hours. But we had printed only as many as we had sent them. There were no extra copies. We finally talked to the printer to get more copies. However, due to festivals and holidays the copies could not be shipped to the online retailer for two days. We knew for sure that they were going to be out of the book for 48 hours. This is the story of how we overcame that situation! Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Load Generator – Free Tool From CodePlex

  - by pinaldave

  One of the most common questions I receive is if there any tool available to generate load on SQL Server. Absolutely there is a fabulous free tool available to generate load on SQL Server on Codeplex. This tool was released in 2008 but it is still extremely relevant to generate the load on SQL Server as well works fabulously. CodePlex is a project initiated by Microsoft for hosting open source softwares. The best part of this SQL Server Load Generator is that users can run multiple simultaneous queries again SQL Server using different login account and different application name. The interface of the tool is extremely easy to use and very intuitive as well. One of the things which I felt needed improvement was a default configuration. As every single time when I was adding a query the default settings were showing up and I had to manually change that. However, when I went to Menu >> Tools >>Options I was really happy as it has options to change every single default which is available. Here one can give default username, password, database name as well various settings related to configuration. Additionally application logging is also possible through the options. A couple of other important points I noticed was the button to reset counters as well status bar containing useful information of Total Threads, Completed Queries and Failed Queries. I use this frequently for my load testing. What tool do you use for SQL Server Load Generator? Download SQL Load Generator Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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• SQL SERVER 2008 – 2011 – Declare and Assign Variable in Single Statement

  - by pinaldave

  Many of us are tend to overlook simple things even if we are capable of doing complex work. In SQL Server 2008, inline variable assignment is available. This feature exists from last 3 years, but I hardly see its utilization. One of the common arguments was that as the project migrated from the earlier version, the feature disappears. I totally accept this argument and acknowledge it. However, my point is that this new feature should be used in all the new coding – what is your opinion? The code which we used in SQL Server 2005 and the earlier version is as follows: DECLARE @iVariable INT, @vVariable VARCHAR(100), @dDateTime DATETIME SET @iVariable = 1 SET @vVariable = 'myvar' SET @dDateTime = GETDATE() SELECT @iVariable iVar, @vVariable vVar, @dDateTime dDT GO The same should be re-written as following: DECLARE @iVariable INT = 1, @vVariable VARCHAR(100) = 'myvar', @dDateTime DATETIME = GETDATE() SELECT @iVariable iVar, @vVariable vVar, @dDateTime dDT GO I have started to use this new method to assign variables as I personally find it very easy to read as well write. Do you still use the earlier method to declare and assign variables? If yes, is there any particular reason or just an old routine? I am interested to hear about this. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Using MAXDOP 1 for Single Processor Query – SQL in Sixty Seconds #008 – Video

  - by pinaldave

  Today’s SQL in Sixty Seconds video is inspired from my presentation at TechEd India 2012 on Speed up! – Parallel Processes and Unparalleled Performance. There are always special cases when it is about SQL Server. There are always few queries which gives optimal performance when they are executed on single processor and there are always queries which gives optimal performance when they are executed on multiple processors. I will be presenting the how to identify such queries as well what are the best practices related to the same. In this quick video I am going to demonstrate if the query is giving optimal performance when running on single CPU how one can restrict queries to single CPU by using hint OPTION (MAXDOP 1). More on Errors: Difference Temp Table and Table Variable – Effect of Transaction Effect of TRANSACTION on Local Variable – After ROLLBACK and After COMMIT Debate – Table Variables vs Temporary Tables – Quiz – Puzzle – 13 of 31 I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Video

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• SQL SERVER – Validating Unique Columnname Across Whole Database

  - by pinaldave

  I sometimes come across very strange requirements and often I do not receive a proper explanation of the same. Here is the one of those examples. Asker: “Our business requirement is when we add new column we want it unique across current database.” Pinal: “Why do you have such requirement?” Asker: “Do you know the solution?” Pinal: “Sure I can come up with the answer but it will help me to come up with an optimal answer if I know the business need.” Asker: “Thanks – what will be the answer in that case.” Pinal: “Honestly I am just curious about the reason why you need your column name to be unique across database.” (Silence) Pinal: “Alright – here is the answer – I guess you do not want to tell me reason.” Option 1: Check if Column Exists in Current Database IF EXISTS (  SELECT * FROM sys.columns WHERE Name = N'NameofColumn') BEGIN SELECT 'Column Exists' -- add other logic END ELSE BEGIN SELECT 'Column Does NOT Exists' -- add other logic END Option 2: Check if Column Exists in Current Database in Specific Table IF EXISTS (  SELECT * FROM sys.columns WHERE Name = N'NameofColumn' AND OBJECT_ID = OBJECT_ID(N'tableName')) BEGIN SELECT 'Column Exists' -- add other logic END ELSE BEGIN SELECT 'Column Does NOT Exists' -- add other logic END I guess user did not want to share the reason why he had a unique requirement of having column name unique across databases. Here is my question back to you – have you faced a similar situation ever where you needed unique column name across a database. If not, can you guess what could be the reason for this kind of requirement?  Additional Reference: SQL SERVER – Query to Find Column From All Tables of Database Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL System Table, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – ERROR – FIX – Msg 3702, Level 16, State 3, Line 1 Cannot drop database “MyDBName” because it is currently in use

  - by pinaldave

  I often go to do various seminars and presentations at various organizations. During presentations I often create and drop various databases for demonstrations purpose. Recently in one of the presentations, I tried to remove my recently created database, I got following error. Msg 3702, Level 16, State 3, Line 1 Cannot drop database “MyDBName” because it is currently in use. The reason was very simple as my database was in use by another session or window. I had option that I should go and find open session and close it right away; later followed by dropping the database. As I was in rush I quickly wrote down following code and I was able to successfully drop the database. USE MASTER GO ALTER DATABASE MyDBName SET SINGLE_USER WITH ROLLBACK IMMEDIATE; DROP DATABASE MyDBName GO Please note that I am doing all this on my demonstrations, do not run above code on production without proper approvals and supervisions. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• MySQL – Export the Resultset to CSV file

  - by Pinal Dave

  In SQL Server, you can use BCP command to export the result set to a csv file. In MySQL too, You can export data from a table or result set as a csv file in many methods. Here are two methods. Method 1 : Make use of Work Bench If you are using Work Bench as a querying tool, you can make use of it’s Export option in the result window. Run the following code in Work Bench SELECT db_names FROM mysql_testing; The result will be shown in the result windows. There is an option called “File”. Click on it and it will prompt you a window to save the result set (Screen shot attached to show how file option can be used). Choose the directory and type out the name of the file. Method 2 : Make use of OUTFILE command You can do the export using a query with OUTFILE command as shown below SELECT db_names FROM mysql_testing INTO OUTFILE 'C:/testing.csv' FIELDS ENCLOSED BY '"' TERMINATED BY ';' ESCAPED BY '"' LINES TERMINATED BY '\r\n'; After the execution of the above code, you can find a file named testing.csv in C drive of the server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: MySQL, PostADay, SQL, SQL Authority, SQL Query, SQL Tips and Tricks, T SQL Tagged: CSV

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• SQL SERVER – Fix: Error: 8117: Operand data type bit is invalid for sum operator

  - by pinaldave

  Here is the very interesting error I received from a reader. He has very interesting question. He attempted to use BIT filed in the SUM aggregation function and he got following error. He went ahead with various different datatype (i.e. INT, TINYINT etc) and he was able to do the SUM but with BIT he faced the problem. Error Received: Msg 8117, Level 16, State 1, Line 1 Operand data type bit is invalid for sum operator. Reproduction of the error: Set up the environment USE tempdb GO -- Preparing Sample Data CREATE TABLE TestTable (ID INT, Flag BIT) GO INSERT INTO TestTable (ID, Flag) SELECT 1, 0 UNION ALL SELECT 2, 1 UNION ALL SELECT 3, 0 UNION ALL SELECT 4, 1 GO SELECT * FROM TestTable GO Following script will work fine: -- This will work fine SELECT SUM(ID) FROM TestTable GO However following generate error: -- This will generate error SELECT SUM(Flag) FROM TestTable GO The workaround is to convert or cast the BIT to INT: -- Workaround of error SELECT SUM(CONVERT(INT, Flag)) FROM TestTable GO Clean up the setup -- Clean up DROP TABLE TestTable GO Workaround: As mentioned in above script the workaround is to covert the bit datatype to another friendly data types like INT, TINYINT etc. 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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• SQL SERVER – Follow up – Usage of $rowguid and $IDENTITY

  - by pinaldave

  The most common question I often receive is why do I blog? The answer is even simpler – I blog because I get an extremely constructive comment and conversation from people like DHall and Kumar Harsh. Earlier this week, I shared a conversation between Madhivanan and myself regarding how to find out if a table uses ROWGUID or not? I encourage all of you to read the conversation here: SQL SERVER – Identifying Column Data Type of uniqueidentifier without Querying System Tables. In simple words the conversation between Madhivanan and myself brought out a simple query which returns the values of the UNIQUEIDENTIFIER  without knowing the name of the column. David Hall wrote few excellent comments as a follow up and every SQL Enthusiast must read them first, second and third. David is always with positive energy, he first of all shows the limitation of my solution here and here which he follows up with his own solution here. As he said his solution is also not perfect but it indeed leaves learning bites for all of us – worth reading if you are interested in unorthodox solutions. Kumar Harsh suggested that one can also find Identity Column used in the table very similar way using $IDENTITY. Here is how one can do the same. DECLARE @t TABLE ( GuidCol UNIQUEIDENTIFIER DEFAULT newsequentialid() ROWGUIDCOL, IDENTITYCL INT IDENTITY(1,1), data VARCHAR(60) ) INSERT INTO @t (data) SELECT 'test' INSERT INTO @t (data) SELECT 'test1' SELECT $rowguid,$IDENTITY FROM @t There are alternate ways also to find an identity column in the database as well. Following query will give a list of all column names with their corresponding tablename. SELECT SCHEMA_NAME(so.schema_id) SchemaName, so.name TableName, sc.name ColumnName FROM sys.objects so INNER JOIN sys.columns sc ON so.OBJECT_ID = sc.OBJECT_ID AND sc.is_identity = 1 Let me know if you use any alternate method related to identity, I would like to know what you do and how you do when you have to deal with Identity Column. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• SQL SERVER – Puzzle to Win Print Book and Free 30 Days Online Training Material

  - by pinaldave

  Yesterday I had asked a simple question SQL SERVER – Puzzle to Win Print Book – Write T-SQL Self Join Without Using LEAD and LAG with keeping two simple intention. We can all learn about new feature of SQL Server 2012 We can learn new feature of SQL Server 2012 while practicing on earlier version of SQL Server. While I was creating question due to copy-paste error the question was not correctly created. In simple word – I made a mistake. This created some confusion and I feel bad about this. Here is what we will do. Please read the question again and attempt to answer the question which I have asked in the blog post. Yesterday the give away was my SQL Server Interview Questions and Answers book. As the question was corrected after a while, the give away are now got sweeter. SQL Server Interview Questions and Answers book – 2 Copy 30 Days Online Training Material of Pluralsight. They have excellent learning resources – I have written my 6 hour learning experience over Learning SSAS (SQL Server Analysis Services) Online in 6 Hours. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLServer, T SQL, Technology

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• MySQL – Grouping by Multiple Columns to Single Column as A String

  - by Pinal Dave

  In this post titled SQL SERVER – Grouping by Multiple Columns to Single Column as A String we have seen how to group multiple column data in comma separate values in a single row grouping by another column by using FOR XML clause. In this post we will see how we can produce the same result using the GROUP_CONCAT function in MySQL. Let us create the following table and data. CREATE TABLE TestTable (ID INT, Col VARCHAR(4)); INSERT INTO TestTable (ID, Col) SELECT 1, 'A' UNION ALL SELECT 1, 'B' UNION ALL SELECT 1, 'C' UNION ALL SELECT 2, 'A' UNION ALL SELECT 2, 'B' UNION ALL SELECT 2, 'C' UNION ALL SELECT 2, 'D' UNION ALL SELECT 2, 'E'; Now to generate csv values of the column col for each ID, use the following code SELECT ID, GROUP_CONCAT(col) AS CSV FROM TestTable GROUP BY ID; The result is ID CSV 1 A,B,C 2 A,B,C,D,E You can also change the delimiters. For example instead of comma, if you want to have a pipe symbol (|), use the following SELECT ID, REPLACE(GROUP_CONCAT(col),',','|') AS CSV FROM TestTable GROUP BY ID; The result is ID CSV 1 A|B|C 2 A|B|C|D|E MySQL makes this very simple with its support of GROUP_CONCAT function. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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