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  • SQLAuthority News – Reliving TechEd with Vinod Kumar at Bangalore User Groups

    - by pinaldave
    TechEd India 2012 was held in Bangalore last March 21 to 23, 2012. Just like every year, this event is bigger, grander and inspiring. Here is my blog post reviewing the event SQLAuthority News – #TechEdIn – TechEd India 2012 Memories and Photos. For me this is family event – I get to meet my friends who are dear as my family. I like to call User Groups as family too. Family shares life’s personal happiness and experience – the same way User Group shares professional experiences and quite often UG members become just like family member. When I learned that follower user group together building up a unique event I was pretty excited to learn who is going to be speaker for the event. BDotNet.in – Bangalore .NET Usergroup BITPro.in – Bangalore ITPro Usergroup It was indeed joy when I learned that presenter will be Vinod Kumar, who is integral part of user groups and hardcore SQL Server enthusiast. Vinod Kumar is going to present on following two sessions which are both focused on internals of the Windows and SQL Server. Understanding Windows with SysInternals Tools – This session will cover various tools from usage of Memory, x86 architecture, x64, WOW mode, Page faults, Virtual Memory mapping, OOM scenario, Perf Tool, PAL tool, Logman and more. Peeling the Onion: SQL Server Internals Demystified – This session will cover advanced disk formats, SQL Server 2012 security changes, memory changes, indirect checkPoint and more. I am very excited as this time I will get opportunity to sit in front rows (as I will be reaching there to get best possible position) and learn. I am looking forward to the event and I hope you will join us as well. Event Details: Date: Saturday, April 7, 2012 (10:30am until 1:30pm) Venue: Microsoft, Domlur, Bangalore. Event Details: https://www.facebook.com/events/139444029517882/ This session is FREE for all and everybody and anybody can walk in. Community Blog Posts Here are few of the blog post written by the community on this subject. Vinod Kumar on Reliving #TechEdIn at Blr UG Manas Dash on Reliving TechEd India 2012 with Vinod Kumar Sudeepta Ganguly on SysInternals n SQLInternals with Vinod Kumar Lohith Re Live TechEd India 2012 with Vinod Kumar  Reference: Pinal Dave (http://blog.sqlauthority.com) http://www.youtube.com/watch?v=oRw-p4mahLU Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL, Technology, Video

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  • SQL SERVER – Detecting Leap Year in T-SQL using SQL Server 2012 – IIF, EOMONTH and CONCAT Function

    - by pinaldave
    Note: Tomorrow is February 29th. This blog post is dedicated to coming tomorrow – a special day :) Subu: “How can I find leap year in using SQL Server 2012?“ Pinal: “Are you asking me how to year 2012 is leap year using T-SQL – search online and you will find many example of the same.” Subu: “No. I am asking – How can I find leap year in using SQL Server 2012?“ Pinal: “Oh so you are asking – How can I find leap year in using SQL Server 2012?“ Subu: “Yeah - How can I find leap year in using SQL Server 2012?“ Pinal: “Let me do that for you – How can you find leap year in using SQL Server 2012?“ Indeed a fun conversation. Honestly, only reason I pasted our conversation here is – it was fun. What he was asking is that how to do it using new functions introduced in SQL Server 2012. Here is the article I have written which introduces all the new functions in SQL Server 2012 Summary of All the Analytic Functions – MSDN and SQLAuthority and 14 New Functions – A Quick Guide. There are many functions written to figure out to figure out if any year is Leap Year or not. The same I have written using T-SQL function over here. CREATE FUNCTION dbo.IsLeapYear (@year INT) RETURNS INT AS BEGIN RETURN(IIF(DATEPART(dd,(EOMONTH(CONCAT(@year,'0201')))) = 29,1,0)) END GO What I really like is that I was able to use three newly introduced function in SQL Server 2012 in above script. You can read more about them here. IIF, EOMONTH and CONCAT. You can validate above query by running following script. SELECT dbo.IsLeapYear('2011') 'IsLeapYear'; SELECT dbo.IsLeapYear('2012') 'IsLeapYear'; GO You will get result 1 if the year is leap year and 0 if year is not leap year. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL DateTime, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Automation Process Good or Ugly

    - by pinaldave
    This blog post is written in response to T-SQL Tuesday hosted by SQL Server Insane Asylum. The idea of this post really caught my attention. Automation – something getting itself done after the initial programming, is my understanding of the subject. The very next thought was – is it good or evil? The reality is there is no right answer. However, what if we quickly note a few things, then I would like to request your help to complete this post. We will start with the positive parts in SQL Server where automation happens. The Good If I start thinking of SQL Server and Automation the very first thing that comes to my mind is SQL Agent, which runs various jobs. Once I configure any task or job, it runs fine (till something goes wrong!). Well, automation has its own advantages. We all have used SQL Agent for so many things – backup, various validation jobs, maintenance jobs and numerous other things. What other kinds of automation tasks do you run in your database server? The Ugly This part is very interesting, because it can get really ugly(!). During my career I have found so many bad automation agent jobs. Client had an agent job where he was dropping the clean buffers every hour Client using database mail to send regular emails instead of necessary alert related emails The best one – A client used new Missing Index and Unused Index scripts in SQL Agent Job to follow suggestions 100%. Believe me, I have never seen such a badly performing and hard to optimize database. (I ended up dropping all non-clustered indexes on the development server and ran production workload on the development server again, then configured with optimal indexes). Shrinking database is performance killer. It should never be automated. SQL SERVER – Shrinking Database is Bad – Increases Fragmentation – Reduces Performance The one I hate the most is AutoShrink Database. It has given me hard time in my career quite a few times. SQL SERVER – SHRINKDATABASE For Every Database in the SQL Server Automation is necessary but common sense is a must when creating automation. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • SQL SERVER – PREEMPTIVE and Non-PREEMPTIVE – Wait Type – Day 19 of 28

    - by pinaldave
    In this blog post, we are going to talk about a very interesting subject. I often get questions related to SQL Server 2008 Book-Online about various Preemptive wait types. I got a few questions asking what these wait types are and how they could be interpreted. To get current wait types of the system, you can read this article and run the script: SQL SERVER – DMV – sys.dm_os_waiting_tasks and sys.dm_exec_requests – Wait Type – Day 4 of 28. Before we continue understanding them, let us study first what PREEMPTIVE and Non-PREEMPTIVE waits in SQL Server mean. PREEMPTIVE: Simply put, this wait means non-cooperative. While SQL Server is executing a task, the Operating System (OS) interrupts it. This leads to SQL Server to involuntarily give up the execution for other higher priority tasks. This is not good for SQL Server as it is a particular external process which makes SQL Server to yield. This kind of wait can reduce the performance drastically and needs to be investigated properly. Non-PREEMPTIVE: In simple terms, this wait means cooperative. SQL Server manages the scheduling of the threads. When SQL Server manages the scheduling instead of the OS, it makes sure its own priority. In this case, SQL Server decides the priority and one thread yields to another thread voluntarily. In the earlier version of SQL Server, there was no preemptive wait types mentioned and the associated task status with them was marked as suspended. In SQL Server 2005, preemptive wait types were not listed as well, but their associated task status was marked as running. In SQL Server 2008, preemptive wait types are properly listed and their associated task status is also marked as running. Now, SQL Server is in Non-Preemptive mode by default and it works fine. When CLR, extended Stored Procedures and other external components run, they run in Preemptive mode, leading to the creation of these wait types. There are a wide variety of preemptive wait types. If you see consistent high value in the Preemptive wait types, I strongly suggest that you look into the wait type and try to know the root cause. If you are still not sure, you can send me an email or leave a comment about it and I will do my best to help you reduce this wait type. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – DMV – sys.dm_os_waiting_tasks and sys.dm_exec_requests – Wait Type – Day 4 of 28

    - by pinaldave
    Previously, we covered the DMV sys.dm_os_wait_stats, and also saw how it can be useful to identify the major resource bottleneck. However, at the same time, we discussed that this is only useful when we are looking at an instance-level picture. Quite often we want to know about the processes going in our server at the given instant. Here is the query for the same. This DMV is written taking the following into consideration: we want to analyze the queries that are currently running or which have recently ran and their plan is still in the cache. SELECT dm_ws.wait_duration_ms, dm_ws.wait_type, dm_es.status, dm_t.TEXT, dm_qp.query_plan, dm_ws.session_ID, dm_es.cpu_time, dm_es.memory_usage, dm_es.logical_reads, dm_es.total_elapsed_time, dm_es.program_name, DB_NAME(dm_r.database_id) DatabaseName, -- Optional columns dm_ws.blocking_session_id, dm_r.wait_resource, dm_es.login_name, dm_r.command, dm_r.last_wait_type FROM sys.dm_os_waiting_tasks dm_ws INNER JOIN sys.dm_exec_requests dm_r ON dm_ws.session_id = dm_r.session_id INNER JOIN sys.dm_exec_sessions dm_es ON dm_es.session_id = dm_r.session_id CROSS APPLY sys.dm_exec_sql_text (dm_r.sql_handle) dm_t CROSS APPLY sys.dm_exec_query_plan (dm_r.plan_handle) dm_qp WHERE dm_es.is_user_process = 1 GO You can change CROSS APPLY to OUTER APPLY if you want to see all the details which are omitted because of the plan cache. Let us analyze the result of the above query and see how it can be helpful to identify the query and the kind of wait type it creates. Click to Enlarage The above query will return various columns. There are various columns that provide very important details. e.g. wait_duration_ms – it indicates current wait for the query that executes at that point of time. wait_type – it indicates the current wait type for the query text – indicates the query text query_plan – when clicked on the same, it will display the query plans There are many other important information like CPU_time, memory_usage, and logical_reads, which can be read from the query as well. In future posts on this series, we will see how once identified wait type we can attempt to reduce the same. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: DMV, Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – SQL in Sixty Seconds – Last Three Episodes – Need Your Opinion

    - by Pinal Dave
    I have been blogging for almost 7 years and building video content for around 2 years. After spending so much time on blogging and creating video, I have got the quite a good idea what people would like to read and what people like to watch. However, there is one thing, which I am constantly struggling after almost a year and I would like to get your opinion about it. Though, this may look very simple to you but it is very crucial to me and I would like to know your opinion about it. I have been building video almost every week for my SQL in Sixty Seconds series and it has been quite popular. So far on my YouTube Channel there are over 2600 subscribers and over 250K views. Here is my problem – there are about 50+ videos on SQL in Sixty Seconds Series but the not every video is popular. There are a few videos which are extremely popular and there are videos which are absolutely struggling to get even single view. I have yet not figured out what people would love to watch on this channel. I noticed lots of people watching various videos but hardly anyone leaving comments or suggestions. At the end of the blog posts associated with the SQL in Sixty Seconds, I always ask which video people would love to watch, but I get a very low response over there too. What I wonder is that why such a low engagement of viewers/readers on the video blog posts where as the channel is success and lots of people are watching the video? What do you think I should change in my video to increase the engagement? Here are my last three videos from SQL in Sixty Seconds channel and I would like to know your feedback. Remove Cached Login from SSMS Connect Dialog – SQL in Sixty Seconds #049 RESEED Identity Column in Database Table – SQL in Sixty Seconds #051 Puzzle SET ANSI_NULLS and Resultset – SQL in Sixty Seconds #052  The feedback which I will like the most will for sure get a special surprise gift for me. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology, Video

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  • SQL SERVER – Puzzle to Win Print Book – Explain Value of PERCENTILE_CONT() Using Simple Example

    - by pinaldave
    From last several days I am working on various Denali Analytical functions and it is indeed really fun to refresh the concept which I studied in the school. Earlier I wrote article where I explained how we can use PERCENTILE_CONT() to find median over here SQL SERVER – Introduction to PERCENTILE_CONT() – Analytic Functions Introduced in SQL Server 2012. Today I am going to ask question based on the same blog post. Again just like last time the intention of this puzzle is as following: Learn new concept of SQL Server 2012 Learn new concept of SQL Server 2012 even if you are on earlier version of SQL Server. On another note, SQL Server 2012 RC0 has been announced and available to download SQL SERVER – 2012 RC0 Various Resources and Downloads. Now let’s have fun following query: USE AdventureWorks GO SELECT SalesOrderID, OrderQty, ProductID, PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY ProductID) OVER (PARTITION BY SalesOrderID) AS MedianCont FROM Sales.SalesOrderDetail WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY SalesOrderID DESC GO The above query will give us the following result: The reason we get median is because we are passing value .05 to PERCENTILE_COUNT() function. Now run read the puzzle. Puzzle: Run following T-SQL code: USE AdventureWorks GO SELECT SalesOrderID, OrderQty, ProductID, PERCENTILE_CONT(0.9) WITHIN GROUP (ORDER BY ProductID) OVER (PARTITION BY SalesOrderID) AS MedianCont FROM Sales.SalesOrderDetail WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY SalesOrderID DESC GO Observe the result and you will notice that MidianCont has different value than before, the reason is PERCENTILE_CONT function has 0.9 value passed. For first four value the value is 775.1. Now run following T-SQL code: USE AdventureWorks GO SELECT SalesOrderID, OrderQty, ProductID, PERCENTILE_CONT(0.1) WITHIN GROUP (ORDER BY ProductID) OVER (PARTITION BY SalesOrderID) AS MedianCont FROM Sales.SalesOrderDetail WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY SalesOrderID DESC GO Observe the result and you will notice that MidianCont has different value than before, the reason is PERCENTILE_CONT function has 0.1 value passed. For first four value the value is 709.3. Now in my example I have explained how the median is found using this function. You have to explain using mathematics and explain (in easy words) why the value in last columns are 709.3 and 775.1 Hint: SQL SERVER – Introduction to PERCENTILE_CONT() – Analytic Functions Introduced in SQL Server 2012 Rules Leave a comment with your detailed answer by Nov 25'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 Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL Contest – Win USD 300 Worth Gift – Cartoon Contest is Back

    - by pinaldave
    There are two excellent contests and we have lots of winning to do this year end. 1) Win USD 25 Amazon Gift Cards (10 Units) This is very simple, you just have to download SQL Server DB Optimizer. That’s it! There are only two conditions: You must have a valid email address. As USD 25 Amazon Gift Card will be sent to the same address. Download DB Optimizer between today and Dec 8, 2012. Link to Download DB Optimizer. Every day one winner will be notified about their winning USD 25 Amazon Gift Cards for next 10 days. 2) Win Star Wars R2-D2 Inflatable R/C This the coolest thing to win. I personally want one but as I am running a contest, I can’t  participate. You get this cool Remote Controlled Device – you just have to answer following cartoon contest. Read the complete story and think what will be the answer provided by the smart employee. There are only two conditions: Leave your answer in the comment area of this blog post (every comment will be hidden till Dec 8, 2012). Please leave your answer in the comment area between today and Dec 8, 2012. Remember you can participate as many times as you want. Make sure that your answer is correct and creative. The most creative answer will be selected. The decision of contest owner will be final. We may have runner’s up prices but for the moment let us try to win R2-D2. Here is the cool video of R2D2. Now here is the cartoon story, please follow the story and complete the very last cartoon template. Your answer should be correct and should be creative. However, the ideal answer will not be longer than one or two sentences. Hint: (Hint) Well, Leave your answer in the comment area of this blog post. If you do not win R2D2, trust me there are chances you may win a surprise gift from me. Remember your answer should be correct and should be creative. However, the ideal answer will not be longer than one or two sentences. Last day to participate in both of the contest is Dec 8, 2012. We will announce the winner in the week of December 10. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, SQLServer, T SQL, Technology

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  • SQL SERVER – Quiz and Video – Introduction to SQL Server Security

    - by pinaldave
    This blog post is inspired from Beginning SQL Joes 2 Pros: The SQL Hands-On Guide for Beginners – SQL Exam Prep Series 70-433 – Volume 1. [Amazon] | [Flipkart] | [Kindle] | [IndiaPlaza] This is follow up blog post of my earlier blog post on the same subject - SQL SERVER – Introduction to SQL Server Security – A Primer. In the article we discussed various basics terminology of the security. The article further covers following important concepts of security. Granting Permissions Denying Permissions Revoking Permissions Above three are the most important concepts related to security 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) If you granted Phil control to the server, but denied his ability to create databases, what would his effective permissions be? Phil can do everything. Phil can do nothing. Phil can do everything except create databases. 2) If you granted Phil control to the server and revoked his ability to create databases, what would his effective permissions be? Phil can do everything. Phil can do nothing. Phil can do everything except create databases. 3) You have a login named James who has Control Server permission. You want to elimintate his ability to create databases without affecting any other permissions. What SQL statement would you use? ALTER LOGIN James DISABLE DROP LOGIN James DENY CREATE DATABASE To James REVOKE CREATE DATABASE To James GRANT CREATE DATABASE To James 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) 3 2) 1 3) 3 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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  • SQL SERVER – Maximize Database Performance with DB Optimizer – SQL in Sixty Seconds #054

    - by Pinal Dave
    Performance tuning is an interesting concept and everybody evaluates it differently. Every developer and DBA have different opinion about how one can do performance tuning. I personally believe performance tuning is a three step process Understanding the Query Identifying the Bottleneck Implementing the Fix While, we are working with large database application and it suddenly starts to slow down. We are all under stress about how we can get back the database back to normal speed. Most of the time we do not have enough time to do deep analysis of what is going wrong as well what will fix the problem. Our primary goal at that time is to just fix the database problem as fast as we can. However, here is one very important thing which we need to keep in our mind is that when we do quick fix, it should not create any further issue with other parts of the system. When time is essence and we want to do deep analysis of our system to give us the best solution we often tend to make mistakes. Sometimes we make mistakes as we do not have proper time to analysis the entire system. Here is what I do when I face such a situation – I take the help of DB Optimizer. It is a fantastic tool and does superlative performance tuning of the system. Everytime when I talk about performance tuning tool, the initial reaction of the people is that they do not want to try this as they believe it requires lots of the learning of the tool before they use it. It is absolutely not true with the case of the DB optimizer. It is a very easy to use and self intuitive tool. Once can get going with the product, in no time. Here is a quick video I have build where I demonstrate how we can identify what index is missing for query and how we can quickly create the index. Entire three steps of the query tuning are completed in less than 60 seconds. If you are into performance tuning and query optimization you should download DB Optimizer and give it a go. Let us see the same concept in following SQL in Sixty Seconds Video: You can Download DB Optimizer and reproduce the same Sixty Seconds experience. Related Tips in SQL in Sixty Seconds: Performance Tuning – Part 1 of 2 – Getting Started and Configuration Performance Tuning – Part 2 of 2 – Analysis, Detection, Tuning and Optimizing What would you like to see in the next SQL in Sixty Seconds video? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Interview Questions and Answers, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Identity

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  • SQL SERVER – Display Datetime in Specific Format – SQL in Sixty Seconds #033 – Video

    - by pinaldave
    A very common requirement of developers is to format datetime to their specific need. Every geographic location has different need of the date formats. Some countries follow the standard of mm/dd/yy and some countries as dd/mm/yy. The need of developer changes as geographic location changes. In SQL Server there are various functions to aid this requirement. There is function CAST, which developers have been using for a long time as well function CONVERT which is a more enhanced version of CAST. In the latest version of SQL Server 2012 a new function FORMAT is introduced as well. In this SQL in Sixty Seconds video we cover two different methods to display the datetime in specific format. 1) CONVERT function and 2) FORMAT function. Let me know what you think of this video. Here is the script which is used in the video: -- http://blog.SQLAuthority.com -- SQL Server 2000/2005/2008/2012 onwards -- Datetime SELECT CONVERT(VARCHAR(30),GETDATE()) AS DateConvert; SELECT CONVERT(VARCHAR(30),GETDATE(),10) AS DateConvert; SELECT CONVERT(VARCHAR(30),GETDATE(),110) AS DateConvert; SELECT CONVERT(VARCHAR(30),GETDATE(),5) AS DateConvert; SELECT CONVERT(VARCHAR(30),GETDATE(),105) AS DateConvert; SELECT CONVERT(VARCHAR(30),GETDATE(),113) AS DateConvert; SELECT CONVERT(VARCHAR(30),GETDATE(),114) AS DateConvert; GO -- SQL Server 2012 onwards -- Various format of Datetime SELECT CONVERT(VARCHAR(30),GETDATE(),113) AS DateConvert; SELECT FORMAT ( GETDATE(), 'dd mon yyyy HH:m:ss:mmm', 'en-US' ) AS DateConvert; SELECT CONVERT(VARCHAR(30),GETDATE(),114) AS DateConvert; SELECT FORMAT ( GETDATE(), 'HH:m:ss:mmm', 'en-US' ) AS DateConvert; GO -- Specific usage of Format function SELECT FORMAT(GETDATE(), N'"Current Time is "dddd MMMM dd, yyyy', 'en-US') AS CurrentTimeString; This video discusses CONVERT and FORMAT in simple manner but the subject is much deeper and there are lots of information to cover along with it. I strongly suggest that you go over related blog posts in next section as there are wealth of knowledge discussed there. Related Tips in SQL in Sixty Seconds: Get Date and Time From Current DateTime – SQL in Sixty Seconds #025 Retrieve – Select Only Date Part From DateTime – Best Practice Get Time in Hour:Minute Format from a Datetime – Get Date Part Only from Datetime DATE and TIME in SQL Server 2008 Function to Round Up Time to Nearest Minutes Interval Get Date Time in Any Format – UDF – User Defined Functions Retrieve – Select Only Date Part From DateTime – Best Practice – Part 2 Difference Between DATETIME and DATETIME2 Saturday Fun Puzzle with SQL Server DATETIME2 and CAST What would you like to see in the next SQL in Sixty Seconds video? 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 Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Excel

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  • SQLAuthority News – Presented at Bangalore DevCon August 4, 2012

    - by pinaldave
    Bangalore Devcon 2012 was a great fun. Earlier this month I was fortunate to be invited to present at Dev Con. The event was very well planned and had excellent response. There were more than 140 attendees at any time in the sessions. There were two tracks and both tracks were running parallel to each other in the Microsoft Bangalore building. The venue is fantastic and the enthusiasm of the community is impeccable. We had a total of 12 sessions during the day. I had decided to attend each session if I can. We have so many fantastic speakers and I did not want to miss any of the sessions. As sessions were running parallel, I attended every session for 30 minutes and switched to another session. I had fun doing this experiment as tit gave me a good idea about every session. I presented personally on the session of SQL Tips and Tricks for Web Developer. DBA is a very common word and every time when we say SQL Server – lots of people think of DBA in their mind, however, SQL Server is used by many developers as well. In this session I tried to cover a few of the simple concepts where developers must pay special attention while writing T-SQL code. Sometimes a very small mistake can be very fatal on performance in the future. Here are few of the photos of the event. Btw, the two sessions which clearly stand out were Vinod Kumar‘s session on Leadership and Lohith‘s session on Visual Studio Tips and Tricks. Additional Read: Following are the blog posts by community on the Bangalore DevCon Experience. I encourage you to read them all and leave a comment which one you liked the most. http://abhishekbhat.wordpress.com/2012/08/07/devcon-2012-experience/ http://praveenprajapati.wordpress.com/2012/08/07/devcon-2012-part-2/ http://tomsblogsspot.blogspot.in/2012/08/devcon-2012.html?view=classic https://manasdash.wordpress.com/2012/08/06/devcon-2012-by-bdotnet-4th-august-2012/ http://www.jagan-bhathri.com/2012/08/bangalore-developer-conference-2012-by.html Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – Rename Columnname or Tablename – SQL in Sixty Seconds #032 – Video

    - by pinaldave
    We all make mistakes at some point of time and we all change our opinion. There are quite a lot of people in the world who have changed their name after they have grown up. Some corrected their parent’s mistake and some create new mistake. Well, databases are not protected from such incidents. There are many reasons why developers may want to change the name of the column or table after it was initially created. The goal of this video is not to dwell on the reasons but to learn how we can rename the column and table. Earlier I have written the article on this subject over here: SQL SERVER – How to Rename a Column Name or Table Name. I have revised the same article over here and created this video. There is one very important point to remember that by changing the column name or table name one creates the possibility of errors in the application the columns and tables are used. When any column or table name is changed, the developer should go through every place in the code base, ad-hoc queries, stored procedures, views and any other place where there are possibility of their usage and change them to the new name. If this is one followed up religiously there are quite a lot of changes that application will stop working due to this name change.  One has to remember that changing column name does not change the name of the indexes, constraints etc and they will continue to reference the old name. Though this will not stop the show but will create visual un-comfort as well confusion in many cases. Here is my question back to you – have you changed ever column name or table name in production database (after project going live)? If yes, what was the scenario and need of doing it. After all it is just a name. Let me know what you think of this video. Here is the updated script. USE tempdb GO CREATE TABLE TestTable (ID INT, OldName VARCHAR(20)) GO INSERT INTO TestTable VALUES (1, 'First') GO -- Check the Tabledata SELECT * FROM TestTable GO -- Rename the ColumnName sp_RENAME 'TestTable.OldName', 'NewName', 'Column' GO -- Check the Tabledata SELECT * FROM TestTable GO -- Rename the TableName sp_RENAME 'TestTable', 'NewTable' GO -- Check the Tabledata - Error SELECT * FROM TestTable GO -- Check the Tabledata - New SELECT * FROM NewTable GO -- Cleanup DROP TABLE NewTable GO Related Tips in SQL in Sixty Seconds: SQL SERVER – How to Rename a Column Name or Table Name What would you like to see in the next SQL in Sixty Seconds video? 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 Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Excel

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  • SQL SERVER – Select and Delete Duplicate Records – SQL in Sixty Seconds #036 – Video

    - by pinaldave
    Developers often face situations when they find their column have duplicate records and they want to delete it. A good developer will never delete any data without observing it and making sure that what is being deleted is the absolutely fine to delete. Before deleting duplicate data, one should select it and see if the data is really duplicate. In this video we are demonstrating two scripts – 1) selects duplicate records 2) deletes duplicate records. We are assuming that the table has a unique incremental id. Additionally, we are assuming that in the case of the duplicate records we would like to keep the latest record. If there is really a business need to keep unique records, one should consider to create a unique index on the column. Unique index will prevent users entering duplicate data into the table from the beginning. This should be the best solution. However, deleting duplicate data is also a very valid request. If user realizes that they need to keep only unique records in the column and if they are willing to create unique constraint, the very first requirement of creating a unique constraint is to delete the duplicate records. Let us see how to connect the values in Sixty Seconds: Here is the script which is used in the video. USE tempdb GO CREATE TABLE TestTable (ID INT, NameCol VARCHAR(100)) GO INSERT INTO TestTable (ID, NameCol) SELECT 1, 'First' UNION ALL SELECT 2, 'Second' UNION ALL SELECT 3, 'Second' UNION ALL SELECT 4, 'Second' UNION ALL SELECT 5, 'Second' UNION ALL SELECT 6, 'Third' GO -- Selecting Data SELECT * FROM TestTable GO -- Detecting Duplicate SELECT NameCol, COUNT(*) TotalCount FROM TestTable GROUP BY NameCol HAVING COUNT(*) > 1 ORDER BY COUNT(*) DESC GO -- Deleting Duplicate DELETE FROM TestTable WHERE ID NOT IN ( SELECT MAX(ID) FROM TestTable GROUP BY NameCol) GO -- Selecting Data SELECT * FROM TestTable GO DROP TABLE TestTable GO Related Tips in SQL in Sixty Seconds: SQL SERVER – Delete Duplicate Records – Rows SQL SERVER – Count Duplicate Records – Rows SQL SERVER – 2005 – 2008 – Delete Duplicate Rows Delete Duplicate Records – Rows – Readers Contribution Unique Nonclustered Index Creation with IGNORE_DUP_KEY = ON – A Transactional Behavior What would you like to see in the next SQL in Sixty Seconds video? 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 Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Excel

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  • SQL SERVER – Online Index Rebuilding Index Improvement in SQL Server 2012

    - by pinaldave
    Have you ever faced situation when you see something working and you feel it should not be working? Well, I had similar moments few days ago. I know that SQL Server 2008 supports online indexing. However, I also know that I cannot rebuild index ONLINE if I have used VARCHAR(MAX), NVARCHAR(MAX) or few other data types. While I held my belief very strongly I came across situation, where I had to go online and do little bit reading from Book Online. Here is the similar example. First of all – run following code in SQL Server 2008 or SQL Server 2008 R2. USE TempDB GO CREATE TABLE TestTable (ID INT, FirstCol NVARCHAR(10), SecondCol NVARCHAR(MAX)) GO CREATE CLUSTERED INDEX [IX_TestTable] ON TestTable (ID) GO CREATE NONCLUSTERED INDEX [IX_TestTable_Cols] ON TestTable (FirstCol) INCLUDE (SecondCol) GO USE [tempdb] GO ALTER INDEX [IX_TestTable_Cols] ON [dbo].[TestTable] REBUILD WITH (ONLINE = ON) GO DROP TABLE TestTable GO Now run the same code in SQL Server 2012 version. Observe the difference between both of the execution. You will be get following resultset. In SQL Server 2008/R2 it will throw following error: Msg 2725, Level 16, State 2, Line 1 An online operation cannot be performed for index ‘IX_TestTable_Cols’ because the index contains column ‘SecondCol’ of data type text, ntext, image, varchar(max), nvarchar(max), varbinary(max), xml, or large CLR type. For a non-clustered index, the column could be an include column of the index. For a clustered index, the column could be any column of the table. If DROP_EXISTING is used, the column could be part of a new or old index. The operation must be performed offline. In SQL Server 2012 it will run successfully and will not throw any error. Command(s) completed successfully. I always thought it will throw an error if there is VARCHAR(MAX) or NVARCHAR(MAX) used in table schema definition. When I saw this result it was clear to me that it will be for sure not bug enhancement in SQL Server 2012. For matter for the fact, I always wanted this feature to be added in SQL Server Engine as this will enable ONLINE Index Rebuilding for mission critical tables which needs to be always online. I quickly searched online and landed on Jacob Sebastian’s blog where he has blogged about it as well. Well, is there any other new feature in SQL Server 2012 which gave you good surprise? 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 – Working with FileTables in SQL Server 2012 – Part 1 – Setting Up Environment

    - by pinaldave
    Filestream is a very interesting feature, and an enhancement of FileTable with Filestream is equally exciting. Today in this post, we will learn how to set up the FileTable Environment in SQL Server. The major advantage of FileTable is it has Windows API compatibility for file data stored within an SQL Server database. In simpler words, FileTables remove a barrier so that SQL Server can be used for the storage and management of unstructured data that are currently residing as files on file servers. Another advantage is that the Windows Application Compatibility for their existing Windows applications enables to see these data as files in the file system. This way, you can use SQL Server to access the data using T-SQL enhancements, and Windows can access the file using its applications. So for the first step, you will need to enable the Filestream feature at the database level in order to use the FileTable. -- Enable Filestream EXEC sp_configure filestream_access_level, 2 RECONFIGURE GO -- Create Database CREATE DATABASE FileTableDB ON PRIMARY (Name = FileTableDB, FILENAME = 'D:\FileTable\FTDB.mdf'), FILEGROUP FTFG CONTAINS FILESTREAM (NAME = FileTableFS, FILENAME='D:\FileTable\FS') LOG ON (Name = FileTableDBLog, FILENAME = 'D:\FileTable\FTDBLog.ldf') WITH FILESTREAM (NON_TRANSACTED_ACCESS = FULL, DIRECTORY_NAME = N'FileTableDB'); GO Now, you can run the following code and figure out if FileStream options are enabled at the database level. -- Check the Filestream Options SELECT DB_NAME(database_id), non_transacted_access, non_transacted_access_desc FROM sys.database_filestream_options; GO You can see the resultset of the above query which returns resultset as the following image shows. As you can see , the file level access is set to 2 (filestream enabled). Now let us create the filetable in the newly created database. -- Create FileTable Table USE FileTableDB GO CREATE TABLE FileTableTb AS FileTable WITH (FileTable_Directory = 'FileTableTb_Dir'); GO Now you can select data using a regular select table. SELECT * FROM FileTableTb GO It will return all the important columns which are related to the file. It will provide details like filesize, archived, file types etc. You can also see the FileTable in SQL Server Management Studio. Go to Databases >> Newly Created Database (FileTableDB) >> Expand Tables Here, you will see a new folder which says “FileTables”. When expanded, it gives the name of the newly created FileTableTb. You can right click on the newly created table and click on “Explore FileTable Directory”. This will open up the folder where the FileTable data will be stored. When you click on the option, it will open up the following folder in my local machine where the FileTable data will be stored: \\127.0.0.1\mssqlserver\FileTableDB\FileTableTb_Dir In tomorrow’s blog post as Part 2, we will go over two methods of inserting the data into this FileTable. 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: Filestream

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  • SQL SERVER – LOGBUFFER – Wait Type – Day 18 of 28

    - by pinaldave
    At first, I was not planning to write about this wait type. The reason was simple- I have faced this only once in my lifetime so far maybe because it is one of the top 5 wait types. I am not sure if it is a common wait type or not, but in the samples I had it really looks rare to me. From Book On-Line: LOGBUFFER Occurs when a task is waiting for space in the log buffer to store a log record. Consistently high values may indicate that the log devices cannot keep up with the amount of log being generated by the server. LOGBUFFER Explanation: The book online definition of the LOGBUFFER seems to be very accurate. On the system where I faced this wait type, the log file (LDF) was put on the local disk, and the data files (MDF, NDF) were put on SanDrives. My client then was not familiar about how the file distribution was supposed to be. Once we moved the LDF to a faster drive, this wait type disappeared. Reducing LOGBUFFER wait: There are several suggestions to reduce this wait stats: Move Transaction Log to Separate Disk from mdf and other files. (Make sure your drive where your LDF is has no IO bottleneck issues). Avoid cursor-like coding methodology and frequent commit statements. Find the most-active file based on IO stall time, as shown in the script written over here. You can also use fn_virtualfilestats to find IO-related issues using the script mentioned over here. Check the IO-related counters (PhysicalDisk:Avg.Disk Queue Length, PhysicalDisk:Disk Read Bytes/sec and PhysicalDisk :Disk Write Bytes/sec) for additional details. Read about them over here. If you have noticed, my suggestions for reducing the LOGBUFFER is very similar to WRITELOG. Although the procedures on reducing them are alike, I am not suggesting that LOGBUFFER and WRITELOG are same wait types. From the definition of the two, you will find their difference. However, they are both related to LOG and both of them can severely degrade the performance. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. 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, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – 2011 – Introduction to SEQUENCE – Simple Example of SEQUENCE

    - by pinaldave
    SQL Server 2011 will contain one of the very interesting feature called SEQUENCE. I have waited for this feature for really long time. I am glad it is here finally. SEQUENCE allows you to define a single point of repository where SQL Server will maintain in memory counter. USE AdventureWorks2008R2 GO CREATE SEQUENCE [Seq] AS [int] START WITH 1 INCREMENT BY 1 MAXVALUE 20000 GO SEQUENCE is very interesting concept and I will write few blog post on this subject in future. Today we will see only working example of the same. Let us create a sequence. We can specify various values like start value, increment value as well maxvalue. -- First Run SELECT NEXT VALUE FOR Seq, c.CustomerID FROM Sales.Customer c GO -- Second Run SELECT NEXT VALUE FOR Seq, c.AccountNumber FROM Sales.Customer c GO Once the sequence is defined, it can be fetched using following method. Every single time new incremental value is provided, irrespective of sessions. Sequence will generate values till the max value specified. Once the max value is reached, query will stop and will return error message. Msg 11728, Level 16, State 1, Line 2 The sequence object ‘Seq’ has reached its minimum or maximum value. Restart the sequence object to allow new values to be generated. We can restart the sequence from any particular value and it will work fine. -- Restart the Sequence ALTER SEQUENCE [Seq] RESTART WITH 1 GO -- Sequence Restarted SELECT NEXT VALUE FOR Seq, c.CustomerID FROM Sales.Customer c GO Let us do final clean up. -- Clean Up DROP SEQUENCE [Seq] GO There are lots of things one can find useful about this feature. We will see that in future posts. Here is the complete code for easy reference. USE AdventureWorks2008R2 GO CREATE SEQUENCE [Seq] AS [int] START WITH 1 INCREMENT BY 1 MAXVALUE 20000 GO -- First Run SELECT NEXT VALUE FOR Seq, c.CustomerID FROM Sales.Customer c GO -- Second Run SELECT NEXT VALUE FOR Seq, c.AccountNumber FROM Sales.Customer c GO -- Restart the Sequence ALTER SEQUENCE [Seq] RESTART WITH 1 GO -- Sequence Restarted SELECT NEXT VALUE FOR Seq, c.CustomerID FROM Sales.Customer c GO -- Clean Up DROP SEQUENCE [Seq] GO 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, SQLServer, T SQL, Technology

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  • SQLAuthority News – First SQL Bangalore Event Report – Nov 24, 2012 – SQL Server User Group Bangalore

    - by pinaldave
    A very common question I often receive - Do we have SQL Server User Group in Bangalore? Yes! SQL Bangalore – we had very first meeting on Nov 24, 2012 and very soon we are going to have another User Group meeting. The goal is to keep up a monthly rhythm of User Group meeting. If you are in Bangalore area please join the Facebook page and you will keep on getting regular update about SQL Server. In the very first meeting we have five 30 minute session and had a fantastic time. We had the best of the best speakers presenting all the five sessions. The event was inaugurated by Vinod Kumar M by presenting on T-SQL Pitfalls. His excellent and eye-opening session was followed by Manas Dash. He enlightened everybody with functions introduced in SQL Server 2012. We had a surprise guest from Mumbai – Raj Chaodhary. If you know him he has a very interesting way to present sessions and he presented on SQL Joins. His hard to follow act was followed by Sudeepta who presented on Contained Database. This subject is quite entertaining and interesting. My session was last in order and I was eagerly waiting to present. I had decided to do something new this time so I had created around 52 slides and two demos. I was committed to go over all the 52 slides and both of the demos in 25 minutes of the time. I had interesting story as well. Though, I was a bit nervous I was able to go over a complete slide deck and demo in 25 minutes of the time I had. We also were very fortunate to have international guest Lynn Langit from USA present at the event as well. She presented an overview of the Big Data in very little time – something not everyone can do it efficiently. We are very thankful to our sponsor Pluralsight for awarding USD 300 worth Annual Subscription. It was the most awaited moment of the day. Well, overall we had a great fun with 100+ attendees learning SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – Tricks to Replace SELECT * with Column Names – SQL in Sixty Seconds #017 – Video

    - by pinaldave
    You might have heard many times that one should not use SELECT * as there are many disadvantages to the usage of the SELECT *. I also believe that there are always rare occasion when we need every single column of the query. In most of the cases, we only need a few columns of the query and we should retrieve only those columns. SELECT * has many disadvantages. Let me list a few and remaining you can add as a comment.  Retrieves unnecessary columns and increases network traffic When a new columns are added views needs to be refreshed manually Leads to usage of sub-optimal execution plan Uses clustered index in most of the cases instead of using optimal index It is difficult to debug. There are two quick tricks I have discussed in the video which explains how users can avoid using SELECT * but instead list the column names. 1) Drag the columns folder from SQL Server Management Studio to Query Editor 2) Right Click on Table Name >> Script TAble AS >> SELECT To… >> Select option It is extremely easy to list the column names in the table. In today’s sixty seconds video, you will notice that I was able to demonstrate both the methods very quickly. From now onwards there should be no excuse for not listing ColumnName. Let me ask a question back – is there ever a reason to SELECT *? If yes, would you please share that as a comment. More on SELECT *: SQL SERVER – Solution – Puzzle – SELECT * vs SELECT COUNT(*) SQL SERVER – Puzzle – SELECT * vs SELECT COUNT(*) SQL SERVER – SELECT vs. SET Performance Comparison I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. If we like your idea we promise to share with you educational material. 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 Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video

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  • SQL SERVER – Manage Help Settings – CTRL + ALT + F1

    - by pinaldave
    It is a miracle that curiosity survives formal education. ~ Albert Einstein I have 3 years old daughter and she never misses any chance to play with the system. I have multiple computers and I always make sure that if I am working with production server, I never leave it open but when I am doing some experiment I often leave my computer open. My daughter loves the part when I have left the computer open and I am not observing her. Recently I had the same scenario, I got urgent call and I moved away from my computer and when I returned she was playing with SSMS left open my computer. Here is the screen which was visible on the screen. For a moment, I could not figure out what was this screen and what was about to get updated. I tried to ask her what keys she pressed the reaction was “I wanted – eya eya o”. Well, what more I expect from 3 years old. She is no computer genius – she just learned to use notepad and paint on my machine. Finally, when I saw the above screen in detail, I realize that this screen was from the help screen and something got updated. I have been using SQL Server for a long time but I never updated help on the screen. When I need to search something if I remember that I have written it earlier I will go to http://search.sqlauthority.com and will search there or will search on Google. As this computer was already updated I fired up Virtual Machine and tried to look recreate how my daughter was reached to above screen. Here are the steps which I have to do to reach to above screen. Go to SSMS >> Toolbar >> Help >> Manage Help Settings (or type CTRL+ALT+F1) and click it. Above click brought up following screen. I clicked on Check for update online brought following screen up. When I clicked on Update it brought me back to original screen which my daughter was able to bring up earlier. I found it so interesting that what took me 2-3 minutes to figure out and the screen which I have never come across in my career I learned from my curiosity like my daughter. 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

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  • SQL SERVER – A Puzzle – Fun with NULL – Fix Error 8117

    - by pinaldave
    During my 8 years of career, I have been involved in many interviews. Quite often, I act as the  interview. If I am the interviewer, I ask many questions – from easy questions to difficult ones. When I am the interviewee, I frequently get an opportunity to ask the interviewer some questions back. Regardless of the my capacity in attending the interview, I always make it a point to ask the interviewer at least one question. What is NULL? It’s always fun to ask this question during interviews, because in every interview, I get a different answer. NULL is often confused with false, absence of value or infinite value. Honestly, NULL is a very interesting subject as it bases its behavior in server settings. There are a few properties of NULL that are universal, but the knowledge about these properties is not known in a universal sense. Let us run this simple puzzle. Run the following T-SQL script: SELECT SUM(data) FROM (SELECT NULL AS data) t It will return the following error: Msg 8117, Level 16, State 1, Line 1 Operand data type NULL is invalid for sum operator. Now the error makes it very clear that NULL is invalid for sum Operator. Frequently enough, I have showed this simple query to many folks whom I came across. I asked them if they could modify the subquery and return the result as NULL. Here is what I expected: Even though this is a very simple looking query, so far I’ve got the correct answer from only 10% of the people to whom I have asked this question. It was common for me to receive this kind of answer – convert the NULL to some data type. However, doing so usually returns the value as 0 or the integer they passed. SELECT SUM(data) FROM (SELECT ISNULL(NULL,0) AS data) t I usually see many people modifying the outer query to get desired NULL result, but that is not allowed in this simple puzzle. This small puzzle made me wonder how many people have a clear understanding about NULL. Well, here is the answer to my simple puzzle. Just CAST NULL AS INT and it will return the final result as NULL: SELECT SUM(data) FROM (SELECT CAST(NULL AS INT) AS data) t Now that you know the answer, don’t you think it was very simple indeed? This blog post is especially dedicated to my friend Madhivanan who has written an excellent blog post about NULL. I am confident that after reading the blog post from Madhivanan, you will have no confusion regarding NULL in the future. Read: NULL, NULL, NULL and nothing but NULL. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Various Leap Year Logics

    - by pinaldave
    Earlier I wrote one article on Leap Year and created one video about Leap Year. My point of view was to demonstrate how we can use SQL Server 2012 features to identify Leap year. How ever during the conversation I had some really good conversation. Here are updates for those who have missed reading the excellent comments on the blog. Incorrect Logic There are so many people still think Leap Year is the event which is consistently happening at every four year and the way to find it is divide the year with 4 and if the remainder is 0. That year is leap year. Well, it is not correct. Comment by David Bridge Check out this excerpt from wikipedia page http://en.wikipedia.org/wiki/Leap_year “most years that are evenly divisible by 4 are leap years…” “…Some exceptions to this rule are required since the duration of a solar year is slightly less than 365.25 days. Years that are evenly divisible by 100 are not leap years, unless they are also evenly divisible by 400, in which case they are leap years. For example, 1600 and 2000 were leap years, but 1700, 1800 and 1900 were not. Similarly, 2100, 2200, 2300, 2500, 2600, 2700, 2900 and 3000 will not be leap years, but 2400 and 2800 will be.” If you use logic of divide by 4 and remainder is 0 to find leap year, you will may end up with inaccurate result. The correct way to identify the year is to figure out the days of February and if the count is 29, the year is for sure leap year. Valid Alternate Solutions Comment by sainswor99insworth IIF((@Year%4=0 AND @Year%100 != 0) OR @Year%400=0, 1,0) Comment by Madhivanan Madhivanan has written a blog post about an year ago where he listed multiple ways to find leap year. Comment by Jayan DECLARE @year INT SET @year = 2012 IF (((@year % 4 = 0) AND (@year % 100 != 0)) OR (@year % 400 = 0)) PRINT ’1' ELSE print ’0' Comment by David DECLARE @Year INT = 2012 SELECT ISDATE('2/29/' + CAST(@Year AS CHAR(4))) Comment by David Bridge Incidentally – Another approach would be to take one day off March 1st and see if it is 29. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL DateTime, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Find Referenced or Referencing Object in SQL Server using sys.sql_expression_dependencies

    - by pinaldave
    A very common question which I often receive are: How do I find all the tables used in a particular stored procedure? How do I know which stored procedures are using a particular table? Both are valid question but before we see the answer of this question – let us understand two small concepts – Referenced and Referencing. Here is the sample stored procedure. CREATE PROCEDURE mySP AS SELECT * FROM Sales.Customer GO Reference: The table Sales.Customer is the reference object as it is being referenced in the stored procedure mySP. Referencing: The stored procedure mySP is the referencing object as it is referencing Sales.Customer table. Now we know what is referencing and referenced object. Let us run following queries. I am using AdventureWorks2012 as a sample database. If you do not have SQL Server 2012 here is the way to get SQL Server 2012 AdventureWorks database. Find Referecing Objects of a particular object Here we are finding all the objects which are using table Customer in their object definitions (regardless of the schema). USE AdventureWorks GO SELECT referencing_schema_name = SCHEMA_NAME(o.SCHEMA_ID), referencing_object_name = o.name, referencing_object_type_desc = o.type_desc, referenced_schema_name, referenced_object_name = referenced_entity_name, referenced_object_type_desc = o1.type_desc, referenced_server_name, referenced_database_name --,sed.* -- Uncomment for all the columns FROM sys.sql_expression_dependencies sed INNER JOIN sys.objects o ON sed.referencing_id = o.[object_id] LEFT OUTER JOIN sys.objects o1 ON sed.referenced_id = o1.[object_id] WHERE referenced_entity_name = 'Customer' The above query will return all the objects which are referencing the table Customer. Find Referenced Objects of a particular object Here we are finding all the objects which are used in the view table vIndividualCustomer. USE AdventureWorks GO SELECT referencing_schema_name = SCHEMA_NAME(o.SCHEMA_ID), referencing_object_name = o.name, referencing_object_type_desc = o.type_desc, referenced_schema_name, referenced_object_name = referenced_entity_name, referenced_object_type_desc = o1.type_desc, referenced_server_name, referenced_database_name --,sed.* -- Uncomment for all the columns FROM sys.sql_expression_dependencies sed INNER JOIN sys.objects o ON sed.referencing_id = o.[object_id] LEFT OUTER JOIN sys.objects o1 ON sed.referenced_id = o1.[object_id] WHERE o.name = 'vIndividualCustomer' The above query will return all the objects which are referencing the table Customer. I am just glad to write above query. There are more to write to this subject. In future blog post I will write more in depth about other DMV which also aids in finding referenced data. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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  • SQLAuthority News – Online Webcast How to Identify Resource Bottlenecks – Wait Types and Queues

    - by pinaldave
    As all of you know I have been working a recently on the subject SQL Server Wait Statistics, the reason is since I have published book on this subject SQL Wait Stats Joes 2 Pros: SQL Performance Tuning Techniques Using Wait Statistics, Types & Queues [Amazon] | [Flipkart] | [Kindle], lots of question and answers I am encountering. When I was writing the book, I kept version 1 of the book in front of me. I wanted to write something which one can use right away. I wanted to create an primer for everybody who have not explored wait stats method of performance tuning. Well, the books have been very well received and in fact we ran out of huge stock 2 times in India so far and once in USA during SQLPASS. I have received so many questions on this subject that I feel I can write one more book of the same size. I have been asked if I can create videos which can go along with this book. Personally I am working with SQL Server 2012 CTP3 and there are so many new wait types, I feel the subject of wait stats is going to be very very crucial in next version of SQL Server. If you have not started learning about this subject, I suggest you at least start exploring this right now. Learn how to begin on this subject atleast as when the next version comes in, you know how to read DMVs. I will be presenting on the same subject of performance tuning by wait stats in webcast embarcadero SQL Server Community Webinar. Here are few topics which we will be covering during the webinar. Beginning with SQL Wait Stats Understanding various aspect of SQL Wait Stats Understanding Query Life Cycle Identifying three TOP wait Stats Resolution of the common 3 wait types and queues Details of the webcast: How to Identify Resource Bottlenecks – Wait Types and Queues Date and Time: Wednesday, November 2, 11:00 AM PDT Registration Link I thank embarcadero for organizing opportunity for me to share my experience on subject of wait stats and connecting me with community to further take this subject to next level. One more interesting thing, I will ask one question at the end of the webinar and I will be giving away 5 copy of my SQL Wait Stats print book to first five correct answers. 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, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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