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  • SQL SERVER – Precision of SMALLDATETIME – A 1 Minute Precision

    - by pinaldave
    I am myself surprised that I am writing this post today. I am going to present one of the very known facts of SQL Server SMALLDATETIME datatype. Even though this is a very well-known datatype, many a time, I have seen developers getting confused with precision of the SMALLDATETIME datatype. The precision of the datatype SMALLDATETIME is 1 minute. It discards the seconds by rounding up or rounding down any seconds greater than zero. Let us see the following example DECLARE @varSDate AS SMALLDATETIME SET @varSDate = '1900-01-01 12:12:01' SELECT @varSDate C_SDT SET @varSDate = '1900-01-01 12:12:29' SELECT @varSDate C_SDT SET @varSDate = '1900-01-01 12:12:30' SELECT @varSDate C_SDT SET @varSDate = '1900-01-01 12:12:59' SELECT @varSDate C_SDT Following is the result of the above script and note that any value between 0 (zero) and 59 is converted up or down. The part that confuses the developers is the value of the seconds in the display. I think if it is not maintained or recorded, it should not be displayed as well. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL DateTime, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – SQL Server Performance Series Hyderabad / Pune – Nov/Dec 2010

    - by pinaldave
    Just a quick note that SQL Server Performance Tuning and Optimizations Seminar series which I am offering at Hyderabad and Pune are almost all sold out. Read the details of the earlier successful seminar conducted at Colombo, Sri Lanka over here. Hyderabad Nov 27-28, 2010 (Last 3 Seats Left) Best Western Amrutha Castle 5-9-16, Opp. Secretriat, Saifabad, Khairatabad Hyderabad, Andhra Pradesh Pune Dec 04-05, 2010 (Last 6 Seats Left) Location TBA as we are looking for larger capacity room. I promise that this is going to be great fun as this sessions are very different then any usual sessions you have ever attended. This sessions are absolutely interactive and all the attendees will feel part of the event. As larger group are not convenient we are limited this seminars to very small group of people. This way attendees can go to instructors any time and feel connected. This 2-day seminar will cover the best of the best concepts and practices from popular courses offered by Solid Quality Mentors. Instead of learning theory only, the seminar focuses on providing real world experience by using demos and scenarios derived from customer engagements. The seminar is uniquely structured and well-thought-out. Sessions are discussion- based and are designed to be an interactive gateway between the instructor and the participants for an optimal learning experience. The seminar is intended to be immersion-based where participants will have plenty of opportunities to get deeply involved in the concepts presented by the instructor. Agenda of the event To join the seminars drop me an email. My email address is pinal “at” SQLAuthority.com and IndiaInfo “at” SolidQ.com. If you specify SQLAuthority.com in Title, you will avail special discount in overall rates on specified price. Yes, a sure 20% I promise. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, Pinal Dave, SQL, SQL Authority, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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  • SQLAuthority News – Bookmark – Deprecated Database Engine Features in SQL Server 2008

    - by pinaldave
    When anybody asked me if any specific feature is available in SQL Server 2008 or if any feature will be disabled in future versions of SQL Server, I always point everybody to following list where all the deprecated database engine features are listed. Deprecated Database Engine Features in SQL Server 2008 R2 Deprecated Database Engine Features in SQL Server 2008 This list is quite helpful and everybody should refer it once. This list has many important details. For example, it suggests “80 compatibility level and upgrade from version 80.” will not be supported in next version of SQL Server. If you are using SQL Server 2000 still today (by any chance) you will be not able to upgrade that to next version of SQL Server directly. It is very important to note that if you are using any feature of SQL Server in compatibility mode and if you find them in the list above. You need to start working on the replacement suggested in article. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Bookmark, SQL, SQL Authority, SQL Documentation, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – Find First Non-Numeric Character from String

    - by pinaldave
    It is fun when you have to deal with simple problems and there are no out of the box solution. I am sure there are many cases when we needed the first non-numeric character from the string but there is no function available to identify that right away. Here is the quick script I wrote down using PATINDEX. The function PATINDEX exists for quite a long time in SQL Server but I hardly see it being used. Well, at least I use it and I am comfortable using it. Here is a simple script which I use when I have to identify first non-numeric character. -- How to find first non numberic character USE tempdb GO CREATE TABLE MyTable (ID INT, Col1 VARCHAR(100)) GO INSERT INTO MyTable (ID, Col1) SELECT 1, '1one' UNION ALL SELECT 2, '11eleven' UNION ALL SELECT 3, '2two' UNION ALL SELECT 4, '22twentytwo' UNION ALL SELECT 5, '111oneeleven' GO -- Use of PATINDEX SELECT PATINDEX('%[^0-9]%',Col1) 'Position of NonNumeric Character', SUBSTRING(Col1,PATINDEX('%[^0-9]%',Col1),1) 'NonNumeric Character', Col1 'Original Character' FROM MyTable GO DROP TABLE MyTable GO Here is the resultset: Where do I use in the real world – well there are lots of examples. In one of the future blog posts I will cover that as well. Meanwhile, do you have any better way to achieve the same. Do share it here. I will write a follow up blog post with due credit to you. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Server, SQL String, SQL Tips and Tricks, T SQL, Technology

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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- Differences Between Left Join and Left Outer Join

    - by pinaldave
    There are a few questions that I had decided not to discuss on this blog because I think they are very simple and many of us know it. Many times, I even receive not-so positive notes from several readers when I am writing something simple. However, assuming that we know all and beginners should know everything is not the right attitude. Since day 1, I have been keeping a small journal regarding questions that I receive in this blog. There are around 200+ questions I receive every day through emails, comments and occasional phone calls. Yesterday, I received a comment with the following question: What are the differences between Left Join and Left Outer Join? Click here to read original comment. This question has triggered the threshold of receiving the same question repeatedly. Here is the answer: There is absolutely no difference between LEFT JOIN and LEFT OUTER JOIN. The same is true for RIGHT JOIN and RIGHT OUTER JOIN. When you use LEFT JOIN keyword in SQL Server, it means LEFT OUTER JOIN only. I have already written in-depth visual diagram discussing the JOINs. I encourage all of you to read the article for further understanding of the JOINs: Read Introduction to JOINs – Basic of JOINs Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Joins, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Reducing Page Contention on TempDB

    - by pinaldave
    I have recently received following email. “We are using TraceFlag 1118 to reduce the tempDB contention on our servers (2000 and 2005). What is your opinion? We have read lots of material, would you please answer me in single line.” Wow, this was very interesting question. What intrigued me was the second last where I am asked to answer in a single line. There is something about this strong email, I feel like blogging it here. I think I can talk over this subject forever – well, there is no clear answer. There are so many caveats about everything.  Again, I must stay honest to the request about answering in single line. I also do not like to answer which is YES/NO. What should I do? Let me ask this question to community today? What will you answer to this email? Let me start this by answering it myself in one line and taking one side. “I enable this trace flag in SQL Server 2000 without hot patch or service pack and not in later versions (2005+) onwards as code is improved”. What do you do in this case? The best answer will feature in this blog with due credit. Regarding further read and hint here is Microsoft KB which I think is very helpful. In quick summary: (Read KB for accuracy) When any page is allocated first 8 pages are allocated in mixed extended. This trace flag allocates uniform extended at the time, reducing contention. You can enable this trace flag at startup. 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 Tagged: SQL TempDB, TempDB

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  • SQL SERVER – Get File Statistics Using fn_virtualfilestats

    - by pinaldave
    Quite often when I am staring at my SSMS I wonder what is going on under the hood in my SQL Server. I often want to know which database is very busy and which database is bit slow because of IO issue. Sometime, I think at the file level as well. I want to know which MDF or NDF is busiest and doing most of the work. Following query gets the same results very quickly. SELECT DB_NAME(vfs.DbId) DatabaseName, mf.name, mf.physical_name, vfs.BytesRead, vfs.BytesWritten, vfs.IoStallMS, vfs.IoStallReadMS, vfs.IoStallWriteMS, vfs.NumberReads, vfs.NumberWrites, (Size*8)/1024 Size_MB FROM ::fn_virtualfilestats(NULL,NULL) vfs INNER JOIN sys.master_files mf ON mf.database_id = vfs.DbId AND mf.FILE_ID = vfs.FileId GO When you run above query you will get many valuable information like what is the size of the file as well how many times the reads and writes are done for each file. It also displays the read/write data in bytes. Due to IO if there has been any stall (delay) in read or write, you can know that as well. I keep this handy but have not shared on blog earlier. 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 View, T SQL, Technology Tagged: Statistics

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  • SQL SERVER – A Funny Cartoon on Index

    - by pinaldave
    Performance Tuning has been my favorite subject and I have done it for many years now. Today I will list one of the most common conversation about Index I have heard in my life. Every single time, I am at consultation for performance tuning I hear following conversation among various team members. I want to ask you, does this kind of conversation happens in your organization? Any way, If you think Index solves all of your performance problem I think it is not true. There are many other reason one has to consider along with Indexes. For example I consider following various topic one need to understand for performance tuning. ?Logical Query Processing ?Efficient Join Techniques ?Query Tuning Considerations ?Avoiding Common Performance Tuning Issues Statistics and Best Practices ?TempDB Tuning ?Hardware Planning ?Understanding Query Processor ?Using SQL Server 2005 and 2008 Updated Feature Sets ?CPU, Memory, I/O Bottleneck Index Tuning (of course) ?Many more… Well, I have written this blog thinking I will keep this blog post a bit easy and not load up. I will in future discuss about other performance tuning concepts. Let me know what do you think about the cartoon I made. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Humor, SQL Index, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – T-SQL Scripts to Find Maximum between Two Numbers

    - by pinaldave
    There are plenty of the things life one can make it simple. I really believe in the same. I was yesterday traveling for community related activity. On airport while returning I met a SQL Enthusiast. He asked me if there is any simple way to find maximum between two numbers in the SQL Server. I asked him back that what he really mean by Simple Way and requested him to demonstrate his code for finding maximum between two numbers. Here is his code: DECLARE @Value1 DECIMAL(5,2) = 9.22 DECLARE @Value2 DECIMAL(5,2) = 8.34 SELECT (0.5 * ((@Value1 + @Value2) + ABS(@Value1 - @Value2))) AS MaxColumn GO I thought his logic was accurate but the same script can be written another way. I quickly wrote following code for him and which worked just fine for him. Here is my code: DECLARE @Value1 DECIMAL(5,2) = 9.22 DECLARE @Value2 DECIMAL(5,2) = 8.34 SELECT CASE WHEN @Value1 > @Value2 THEN @Value1 ELSE @Value2 END AS MaxColumn GO He agreed that my code is much simpler but as per him there is some problem with my code which apparently he does not remember at this time. There are cases when his code will give accurate values and my code will not. I think his comment has value but both of us for the moment could not come up with any valid reason. Do you think any scenario where his code will work and my suggested code will not work? 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 – Two Puzzles – Answer and Win USD 25 Gift Card

    - by pinaldave
    Today I have two simple T-SQL Puzzle. You can answer them and win USD 25 Gift card. The gift card will be sent in email to winner. You will get choice of Gift Card brand based on your preference and country location. Puzzle 1: What will be the outcome and why? DECLARE @x REAL; SET @x = 9E-40 SELECT @x; The outcome here is obvious as I have used negative number in assignment. What is the reason behind the same? Puzzle 2: Why will be the outcome different from Puzzle 1: DECLARE @y REAL; SET @y = 9E+40 SELECT @y; The outcome of this puzzle very different from puzzle 1  as I have used positive number. There is number six (6) in the resultset why? Msg 232, Level 16, State 2, Line 2 Arithmetic overflow error for type real, value = 90000000000000006000000000000000000000000.000000. How to participate To win the Gift Card USD 25 you will have to answer both of the question on my Facebook page. If you are on twitter – you can increase the chance of winning by tweeting your participation. This contest is open for any one from any country. The winner will be selected Randomly. Winner will be announced on July 7, 2011. Related Post: SQLAuthority News – Monthly list of Puzzles and Solutions on SQLAuthority.com Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • SQL SERVER – 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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  • SQL SERVER – Auditing and Profiling Database Made Easy with SQL Audit and Comply

    - by Pinal Dave
    Do you like auditing your database, or can you think of about a million other things you’d rather do?  Unfortunately, auditing is incredibly important.  As with tax audits, it is important to audit databases to ensure they are following all the rules, but they are also important for troubleshooting and security. There are several ways to audit SQL Server.  There is manual auditing, which is going through your database “by hand,” and obviously takes a long time and is quite inefficient.  SQL Server also provides programs to help you audit your systems.  Different administrators will have different opinions about best practices and which tools to use, and each one will be perfected for certain systems and certain users. Today, though, I would like to talk about Apex SQL Audit.  It is an auditing tool that acts like “track changes” in a word processing document.  It will log what has changed on the database, who made the changes, and what effects these changes have had (i.e. what objects were affected down the line).  All this information is logged, and can be easily viewed or printed for easy access. One of the best features of Apex is that it is so customizable (and easy to use!).  First, start Apex.  Then you can connect to the database you would like to monitor. Once you select your database, you can select which table you want to audit. You can customize right down to the field you’d like to audit, and then select which types of actions you’d like tracked – insert, delete, or update.  Repeat these steps for every database you want monitored. To create the logs, choose “Create triggers” in the menu.  The script written here will be what logs each insert, delete, and update function.  Press F5 to execute.  All this tracking information will be stored in AUDIT_LOG_DATA and AUDIT_LOG_TRANSACTIONS tables.  View these tables using ApexSQL Audit reports. These transaction logs can be extremely detailed – especially on very busy servers, where every move it traced.  Reading them can be overwhelming, to say the least.  Apex has tried to make things easier for the average DBA, though. You can read these tracking logs in Apex, and it will display data and objects that affect your server – even things that were happening on your server before you installed Apex! To read these logs, open Apex, and connect to that database you want to audit. Go to the Transaction Logs tab, and add the logs you want to read. To narrow down what results you want to see, you can use the Filter tab to choose time, operation type, name, users, and more. Click Open, and you can see the results in a grid (as shown below).  You can export these results to CSV, HTML, XML or SQL files and save on the hard disk. One of the advantages is that since there are no triggers here, there are no other processes that will affect SQL Server performance.  Using this method is also how to view history from your database that occurred before Apex was installed.  This type of tracking does require storage space for the data sources, as the database must be fully running, and the transaction logs must exist (things not stored in the transactions logs will not be recoverable). Apex can also replace SQL Server Profiler and SQL Server Traces – which are much more complex and error-prone – with its ApexSQL Comply.  It can do fault tolerant auditing, centralized reporting, and “who saw what” information in an easy-to-use interface.  The tracking settings can be altered by the user, or the default options will provide solutions to the most common auditing problems. To get started: open ApexSQL Comply, and selected Database Filter Settings to choose which database you’d like to audit.  You can select which tracking you’re like in Operation Types – DML, DDL, queries executed, execute statements, and more.  To get started, click Start Auditing. After this, every action will be stored in the central repository database (ApexSQLCrd).  You can view the audit and create a report (or view the standard default report) using a wizard. You can see how easy it is to use ApexSQL Comply.  You can easily set audits, including the type and time, and create customized reports.  Remote users can easily access the reports through the user interface (available online, as well), and security concerns are all taken care of by the program.  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 – Pending IO request in SQL Server – DMV

    - by pinaldave
    I received following question: “How do we know how many pending IO requests are there for database files (.mdf, .ldf) individually?” Very interesting question and indeed answer is very interesting as well. Here is the quick script which I use to find the same. It has to be run in the context of the database for which you want to know pending IO statistics. USE DATABASE GO SELECT vfs.database_id, df.name, df.physical_name ,vfs.FILE_ID, ior.io_pending FROM sys.dm_io_pending_io_requests ior INNER JOIN sys.dm_io_virtual_file_stats (DB_ID(), NULL) vfs ON (vfs.file_handle = ior.io_handle) INNER JOIN sys.database_files df ON (df.FILE_ID = vfs.FILE_ID) I keep this script handy as it works like magic every time. If you use any other script please post here and I will post it with due credit. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Finding Shortest Distance between Two Shapes using Spatial Data Classes – Ramsetu or Adam’s Bridge

    - by pinaldave
    Recently I was reading excellent blog post by Lenni Lobel on Spatial Database. He has written very interesting function ShortestLineTo in Spatial Data Classes. I really loved this new feature of the finding shortest distance between two shapes in SQL Server. Following is the example which is same as Lenni talk on his blog article . DECLARE @Shape1 geometry = 'POLYGON ((-20 -30, -3 -26, 14 -28, 20 -40, -20 -30))' DECLARE @Shape2 geometry = 'POLYGON ((-18 -20, 0 -10, 4 -12, 10 -20, 2 -22, -18 -20))' SELECT @Shape1 UNION ALL SELECT @Shape2 UNION ALL SELECT @Shape1.ShortestLineTo(@Shape2).STBuffer(.25) GO When you run this script SQL Server finds out the shortest distance between two shapes and draws the line. We are using STBuffer so we can see the connecting line clearly. Now let us modify one of the object and then we see how the connecting shortest line works. DECLARE @Shape1 geometry = 'POLYGON ((-20 -30, -3 -30, 14 -28, 20 -40, -20 -30))' DECLARE @Shape2 geometry = 'POLYGON ((-18 -20, 0 -10, 4 -12, 10 -20, 2 -22, -18 -20))' SELECT @Shape1 UNION ALL SELECT @Shape2 UNION ALL SELECT @Shape1.ShortestLineTo(@Shape2).STBuffer(.25) GO Now once again let us modify one of the script and see how the shortest line to works. DECLARE @Shape1 geometry = 'POLYGON ((-20 -30, -3 -30, 14 -28, 20 -40, -20 -30))' DECLARE @Shape2 geometry = 'POLYGON ((-18 -20, 0 -10, 4 -12, 10 -20, 2 -18, -18 -20))' SELECT @Shape1 UNION ALL SELECT @Shape2 UNION ALL SELECT @Shape1.ShortestLineTo(@Shape2).STBuffer(.25) SELECT @Shape1.STDistance(@Shape2) GO You can see as the objects are changing the shortest lines are moving at appropriate place. I think even though this is very small feature this is really cool know. While I was working on this example, I suddenly thought about distance between Sri Lanka and India. The distance is very short infect it is less than 30 km by sea. I decided to map India and Sri Lanka using spatial data classes. To my surprise the plotted shortest line is the same as Adam’s Bridge or Ramsetu. Adam’s Bridge starts as chain of shoals from the Dhanushkodi tip of India’s Pamban Island and ends at Sri Lanka’s Mannar Island. Geological evidence suggests that this bridge is a former land connection between India and Sri Lanka. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Spatial Database, SQL Spatial

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  • SQL SERVER – Importance of User Without Login – T-SQL Demo Script

    - by pinaldave
    Earlier I wrote a blog post about SQL SERVER – Importance of User Without Login and my friend and SQL Expert Vinod Kumar has written excellent follow up blog post about Contained Databases inside SQL Server 2012. Now lots of people asked me if I can also explain the same concept again so here is the small demonstration for it. Let me show you how login without user can help. Before we continue on this subject I strongly recommend that you read my earlier blog post here. In following demo I am going to demonstrate following situation. Login using the System Admin account Create a user without login Checking Access Impersonate the user without login Checking Access Revert Impersonation Give Permission to user without login Impersonate the user without login Checking Access Revert Impersonation Clean up USE [AdventureWorks2012] GO -- Step 1 : Login using the SA -- Step 2 : Create Login Less User CREATE USER [testguest] 9ITHOUT LOGIN WITH DEFAULT_SCHEMA=[dbo] GO -- Step 3 : Checking access to Tables SELECT * FROM sys.tables; -- Step 4 : Changing the execution contest EXECUTE AS USER   = 'testguest'; GO -- Step 5 : Checking access to Tables SELECT * FROM sys.tables; GO -- Step 6 : Reverting Permissions REVERT; -- Step 7 : Giving more Permissions to testguest user GRANT SELECT ON [dbo].[ErrorLog] TO [testguest]; GRANT SELECT ON [dbo].[DatabaseLog] TO [testguest]; GO -- Step 8 : Changing the execution contest EXECUTE AS USER   = 'testguest'; GO -- Step 9 : Checking access to Tables SELECT * FROM sys.tables; GO -- Step 10 : Reverting Permissions REVERT; GO -- Step 11: Clean up DROP USER [testguest]Step 3 GO Here is the step 9 we will be able to notice that how a user without login gets access to some of the data/object which we gave permission. What I am going to prove with this example? Well there can be different rights with different account. Once the login is authenticated it makes sense for impersonating a user with only necessary permissions to be used for further operation. Again this is very basic and fundamental example. There are lots of more points to be discussed as we go in future posts. Just do not take this blog post as a template and implement everything as it is. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Security, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Monday Morning Puzzle – Query Returns Results Sometimes but Not Always

    - by pinaldave
    The amount of email I receive sometime it is impossible for me to answer every email. Nonetheless I try to answer pretty much every email I receive. However, quite often I receive such questions in email that I have no answer to them because either emails are not complete or they are out of my domain expertise. In recent times I received one email which had only one or two lines but indeed attracted my attention to it. The question was bit vague but it indeed made me think. The answer was not straightforward so I had to keep on writing the answer as I remember it. However, after writing the answer I do not feel satisfied. Let me put this question in front of you and see if we all can come up with a comprehensive answer. Question: 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. Well, if you read the question, it is indeed incomplete and it does not contain much of the information at all. I decided to help him and here is the answer, which I started to compose. Answer: As there are not much information in the original question, I am not confident what will solve your problem. However, here are the few things which you can try to look at and see if that solves your problem. Check parameter which is passed to the query. Is the parameter changing at various executions? Check connection string – is there some kind of logic around it? Do you have a non-deterministic component in your query logic? (In other words – does your result is based on current date time or any other time based function?) Are you facing time out while running your query? Is there any error in error log? What is the business logic in your query? Do you have all the valid permissions to all the objects used in the query? Are permissions changing or query accessing a different object in various executions? (Add your suggestions here) Meanwhile, have you ever faced this situation? If yes, do share your experience in the comment area. I will send a copy of my book SQL Server Interview Questions and Answers to one of the most interesting comment. The winner will be announced by next Monday.  Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Interview Questions and Answers, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Iridium I/O – SQL Server Deduplication that Shrinks Databases and Improves Performance

    - by Pinal Dave
    Database performance is a common problem for SQL Server DBA’s.  It seems like we spend more time on performance than just about anything else.  In many cases, we use scripts or tools that point out performance bottlenecks but we don’t have any way to fix them.  For example, what do you do when you need to speed up a query that is already tuned as well as possible?  Or what do you do when you aren’t allowed to make changes for a database supporting a purchased application? Iridium I/O for SQL Server was originally built at Confio software (makers of Ignite) because DBA’s kept asking for a way to actually fix performance instead of just pointing out performance problems. The technology is certified by Microsoft and was so promising that it was spun out into a separate company that is now run by the Confio Founder/CEO and technology management team. Iridium uses deduplication technology to both shrink the databases as well as boost IO performance.  It is intriguing to see it work.  It will deduplicate a live database as it is running transactions.  You can watch the database get smaller while user queries are running. Iridium is a simple tool to use. After installing the software, you click an “Analyze” button which will spend a minute or two on each database and estimate both your storage and performance savings.  Next, you click an “Activate” button to turn on Iridium I/O for your selected databases.  You don’t need to reboot the operating system or restart the database during any part of the process. As part of my test, I also wanted to see if there would be an impact on my databases when Iridium was removed.  The ‘revert’ process (bringing the files back to their SQL Server native format) was executed by a simple click of a button, and completed while the databases were available for normal processing. I was impressed and enjoyed playing with the software and encourage all of you to try it out.  Here is the link to the website to download Iridium for free. . Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • SQL SERVER – Replace a Column Name in Multiple Stored Procedure all together

    - by pinaldave
    I receive a lot of emails every day. I try to answer each and every email and comments on Facebook and Twitter. I prefer communication on social media as this gives opportunities to others to read the questions and participate along with me. There is always some question which everyone likes to read and remember. Here is one of the questions which I received in email. I believe the same question will be there any many developers who are beginning with SQL Server. I decided to blog about it so everyone can read it and participate. “I am beginner in SQL Server. I have a very interesting situation and need your help. I am beginner to SQL Server and that is why I do not have access to the production server and I work entirely on the development server. The project I am working on is also in the infant stage as well. In product I had to create a multiple tables and every table had few columns. Later on I have written Stored Procedures using those tables. During a code review my manager has requested to change one of the column which I have used in the table. As per him the naming convention was not accurate. Now changing the columname in the table is not a big issue. I figured out that I can do it very quickly either using T-SQL script or SQL Server Management Studio. The real problem is that I have used this column in nearly 50+ stored procedure. This looks like a very mechanical task. I believe I can go and change it in nearly 50+ stored procedure but is there a better solution I can use. Someone suggested that I should just go ahead and find the text in system table and update it there. Is that safe solution? If not, what is your solution. In simple words, How to replace a column name in multiple stored procedure efficiently and quickly? Please help me here with keeping my experience and non-production server in mind.” Well, I found this question very interesting. Honestly I would have preferred if this question was asked on my social media handles (Facebook and Twitter) as I am very active there and quite often before I reach there other experts have already answered this question. Anyway I am now answering the same question on the blog so all of us can participate here and come up with an appropriate answer. Here is my answer - “My Friend, I do not advice to touch system table. Please do not go that route. It can be dangerous and not appropriate. The issue which you faced today is what I used to face in early career as well I still face it often. There are two sets of argument I have observed – there are people who see no value in the name of the object and name objects like obj1, obj2 etc. There are sets of people who carefully chose the name of the object where object name is self-explanatory and almost tells a story. I am not here to take any side in this blog post – so let me go to a quick solution for your problem. Note: Following should not be directly practiced on Production Server. It should be properly tested on development server and once it is validated they should be pushed to your production server with your existing deployment practice. The answer is here assuming you have regular stored procedures and you are working on the Development NON Production Server. Go to Server Note >> Databases >> DatabaseName >> Programmability >> Stored Procedure Now make sure that Object Explorer Details are open (if not open it by clicking F7). You will see the list of all the stored procedures there. Now you will see a list of all the stored procedures on the right side list. Select either all of them or the one which you believe are relevant to your query. Now… Right click on the stored procedures >> SELECT DROP and CREATE to >> Now select New Query Editor Window or Clipboard. Paste the complete script to a new window if you have selected Clipboard option. Now press Control+H which will bring up the Find and Replace Screen. In this screen insert the column to be replaced in the “Find What”box and new column name into “Replace With” box. Now execute the whole script. As we have selected DROP and CREATE to, it will created drop the old procedure and create the new one. Another method would do all the same procedure but instead of DROP and CREATE manually replace the CREATE word with ALTER world. There is a small advantage in doing this is that if due to any reason the error comes up which prevents the new stored procedure to be created you will have your old stored procedure in the system as it is. “ Well, this was my answer to the question which I have received. Do you see any other workaround or solution? Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Stored Procedure, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Create Primary Key with Specific Name when Creating Table

    - by pinaldave
    It is interesting how sometimes the documentation of simple concepts is not available online. I had received email from one of the reader where he has asked how to create Primary key with a specific name when creating the table itself. He said, he knows the method where he can create the table and then apply the primary key with specific name. The attached code was as follows: CREATE TABLE [dbo].[TestTable]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL) GO ALTER TABLE [dbo].[TestTable] ADD  CONSTRAINT [PK_TestTable] PRIMARY KEY CLUSTERED ([ID] ASC) GO He wanted to know if we can create Primary Key as part of the table name as well, and also give it a name at the same time. Though it would look very normal to all experienced developers, it can be still confusing to many. Here is the quick code that functions as the above code in one single statement. CREATE TABLE [dbo].[TestTable]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL CONSTRAINT [PK_TestTable] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, Readers Question, SQL, SQL Authority, SQL Constraint and Keys, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Repair a SQL Server Database Using a Transaction Log Explorer

    - by Pinal Dave
    In this blog, I’ll show how to use ApexSQL Log, a SQL Server transaction log viewer. You can download it for free, install, and play along. But first, let’s describe some disaster recovery scenarios where it’s useful. About SQL Server disaster recovery Along with database development and administration, you must work on a good recovery plan. Disasters do happen and no one’s immune. What you can do is take all actions needed to be ready for a disaster and go through it with minimal data loss and downtime. Besides creating a recovery plan, it’s necessary to have a list of steps that will be executed when a disaster occurs and to test them before a disaster. This way, you’ll know that the plan is good and viable. Testing can also be used as training for all team members, so they can all understand and execute it when the time comes. It will show how much time is needed to have your servers fully functional again and how much data you can lose in a real-life situation. If these don’t meet recovery-time and recovery-point objectives, the plan needs to be improved. Keep in mind that all major changes in environment configuration, business strategy, and recovery objectives require a new recovery plan testing, as these changes most probably induce a recovery plan changing and tweaking. What is a good SQL Server disaster recovery plan? A good SQL Server disaster recovery strategy starts with planning SQL Server database backups. An efficient strategy is to create a full database backup periodically. Between two successive full database backups, you can create differential database backups. It is essential is to create transaction log backups regularly between full database backups. Keep in mind that transaction log backups can be created only on databases in the full recovery model. In other words, a simple, but efficient backup strategy would be a full database backup every night, a transaction log backup every hour, or every 15 minutes. The frequency depends on how much data you can afford to lose and how busy the database is. Another option, instead of creating a full database backup every night, is to create a full database backup once a week (e.g. on Friday at midnight) and differential database backup every night until next Friday when you will create a full database backup again. Once you create your SQL Server database backup strategy, schedule the backups. You can do that easily using SQL Server maintenance plans. Why are transaction logs important? Transaction log backups contain transactions executed on a SQL Server database. They provide enough information to undo and redo the transactions and roll back or forward the database to a point in time. In SQL Server disaster recovery situations, transaction logs enable to repair a SQL Server database and bring it to the state before the disaster. Be aware that even with regular backups, there will be some data missing. These are the transactions made between the last transaction log backup and the time of the disaster. In some situations, to repair your SQL Server database it’s not necessary to re-create the database from its last backup. The database might still be online and all you need to do is roll back several transactions, such as wrong update, insert, or delete. The restore to a point in time feature is available in SQL Server, but for large databases, it is very time-consuming, as SQL Server first restores a full database backup, and then restores transaction log backups, one after another, up to the recovery point. During that time, the database is unavailable. This is where a SQL Server transaction log viewer can help. For optimal recovery, besides having a database in the full recovery model, it’s important that you haven’t manually truncated the online transaction log. This ensures that all transactions made after the last transaction log backup are still in the online transaction log. All you have to do is read and replay them. How to read a SQL Server transaction log? SQL Server doesn’t provide an option to read transaction logs. There are several SQL Server commands and functions that read the content of a transaction log file (fn_dblog, fn_dump_dblog, and DBCC PAGE), but they are undocumented. They require T-SQL knowledge, return a large number of not easy to read and understand columns, sometimes in binary or hexadecimal format. Another challenge is reading UPDATE statements, as it’s necessary to match it to a value in the MDF file. When you finally read the transactions executed, you have to create a script for it. How to easily repair a SQL database? The easiest solution is to use a transaction log reader that will not only read the transactions in the transaction log files, but also automatically create scripts for the read transactions. In the following example, I will show how to use ApexSQL Log to repair a SQL database after a crash. If a database has crashed and both MDF and LDF files are lost, you have to rely on the full database backup and all subsequent transaction log backups. In another scenario, the MDF file is lost, but the LDF file is available. First, restore the last full database backup on SQL Server using SQL Server Management Studio. I’ll name it Restored_AW2014. Then, start ApexSQL Log It will automatically detect all local servers. If not, click the icon right to the Server drop-down list, or just type in the SQL Server instance name. Select the Windows or SQL Server authentication type and select the Restored_AW2014 database from the database drop-down list. When all options are set, click Next. ApexSQL Log will show the online transaction log file. Now, click Add and add all transaction log backups created after the full database backup I used to restore the database. In case you don’t have transaction log backups, but the LDF file hasn’t been lost during the SQL Server disaster, add it using Add.   To repair a SQL database to a point in time, ApexSQL Log needs to read and replay all the transactions in the transaction log backups (or the LDF file saved after the disaster). That’s why I selected the Whole transaction log option in the Filter setup. ApexSQL Log offers a range of various filters, which are useful when you need to read just specific transactions. You can filter transactions by the time of the transactions, operation type (e.g. to read only data inserts), table name, SQL Server login that made the transaction, etc. In this scenario, to repair a SQL database, I’ll check all filters and make sure that all transactions are included. In the Operations tab, select all schema operations (DDL). If you omit these, only the data changes will be read so if there were any schema changes, such as a new function created, or an existing table modified, they will be ignored and database will not be properly repaired. The data repair for modified tables will fail. In the Tables tab, I’ll make sure all tables are selected. I will uncheck the Show operations on dropped tables option, to reduce the number of transactions. Click Next. ApexSQL Log offers three options. Select Open results in grid, to get a user-friendly presentation of the transactions. As you can see, details are shown for every transaction, including the old and new values for updated columns, which are clearly highlighted. Now, select them all and then create a redo script by clicking the Create redo script icon in the menu.   For a large number of transactions and in a critical situation, when acting fast is a must, I recommend using the Export results to file option. It will save some time, as the transactions will be directly scripted into a redo file, without showing them in the grid first. Select Generate reconstruction (REDO) script , change the output path if you want, and click Finish. After the redo T-SQL script is created, ApexSQL Log shows the redo script summary: The third option will create a command line statement for a batch file that you can use to schedule execution, which is not really applicable when you repair a SQL database, but quite useful in daily auditing scenarios. To repair your SQL database, all you have to do is execute the generated redo script using an integrated developer environment tool such as SQL Server Management Studio or any other, against the restored database. You can find more information about how to read SQL Server transaction logs and repair a SQL database on ApexSQL Solution center. There are solutions for various situations when data needs to be recovered, restored, or transactions rolled back. 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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  • SQL SERVER – Copy Statistics from One Server to Another Server

    - by pinaldave
    I was recently working on a performance tuning project in Dubai (yeah I was able to see the tallest tower from the window of my work place). I had a very interesting learning experience there. There was a situation where we wanted to receive the schema of original database from a certain client. However, the client was not able to provide us any data due to privacy issues. The schema was very important because without having an access to underlying data, it was a bit difficult to judge the queries etc. For example, without any primary data, all the queries are running in 0 (zero) milliseconds and all were using nested loop as there were no data to be returned. Even though we had CPU offending queries, they were not doing anything without the data in the tables. This was really a challenge as I did not have access to production server data and I could not recreate the scenarios as production without data. Well, I was confused but Ruben from Solid Quality Mentors, Spain taught me new tricks. He suggested that when table schema is generated, we can create the statistics consequently. Here is how we had done that: Once statistics is created along with the schema, without data in the table, all the queries will work as how they will work on production server. This way, without access to the data, we were able to recreate the same scenario as production server on development server. When observed at the script, you will find that the statistics were also generated along with the query. You will find statistics included in WITH STATS_STREAM clause. What a very simple and effective script. 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 Tagged: SQL Statistics, Statistics

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  • SQL SERVER – Determine if SSRS 2012 is Installed on your SQL Server

    - by Pinal Dave
    This example is from the Beginning SSRS by Kathi Kellenberger. Supporting files are available with a free download from the www.Joes2Pros.com web site. Determine if SSRS 2012 is Installed on your SQL Server You may already have SSRS, or you may need to install it. Before doing any installation it makes sense to know where you are now. If you happened to install SQL Server with all features, you have the tools you need. There are two tools you need: SQL Server Data Tools and Reporting Services installed in Native Mode. To find out if SQL Server Data Tools (SSDT) is installed, click the Start button, go to All Programs, and expand SQL Server 2012. Look for SQL Server Data Tools   Now, let’s check to see if SQL Server Reporting Services is installed. Click the Start > All Programs > SQL Server 2012 > Configuration Tools > SQL > Server Configuration Manager   Once Configuration Manager is running, select SQL Server Services. Look for SQL Server Reporting Services in the list of services installed. If you have both SQL Server Reporting Services service and SQL Server Developer tools installed, you will not have to install them again. You may have SQL Server installed, but are missing the Data Tools or the SSRS service or both. In tomorrow blog post we will go over how to install based on where you are now.   Tomorrow’s Post Tomorrow’s blog post will show how to install and configure SSRS. If you want to learn SSRS in easy to simple words – I strongly recommend you to get Beginning SSRS book from Joes 2 Pros. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Reporting Services, SSRS

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  • SQL SERVER – Right Aligning Numerics in SQL Server Management Studio (SSMS)

    - by pinaldave
    SQL Server Management Studio is my most favorite tool and the comfort it provides to user is sometime very amazing. Recently I was retrieving numeric data in SSMS and I found it is very difficult to read them as they were all right aligned. Please pay attention to following image, you will notice that it is not easier to read the digits as we are used to read the numbers which are right aligned. I immediately thought before I go for any other tricks I should check the query properties. I right clicked on query properties and I found following option. I checked option Right align numeric values and it just worked fine. Do you have any other similar tricks which do you practice often. I prefer to also include column headers in the result set as it gives me proper perspective of which column I have selected. Sometime little tips like this helps a lot in productivity, I encourage you to share your tips. I will publish it with due credit. 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 – Function to Round Up Time to Nearest Minutes Interval

    - by pinaldave
    Though I have written more than 2300 blog posts, I always find things which I have not covered earlier in this blog post. Recently I was asked if I have written a function which rounds up or down the time based on the minute interval passed to it. Well, not earlier but it is here today. Here is a very simple example of how one can do the same. ALTER FUNCTION [dbo].[RoundTime] (@Time DATETIME, @RoundToMin INT) RETURNS DATETIME AS BEGIN RETURN ROUND(CAST(CAST(CONVERT(VARCHAR,@Time,121) AS DATETIME) AS FLOAT) * (1440/@RoundToMin),0)/(1440/@RoundToMin) END GO Above function needs two values. 1) The time which needs to be rounded up or down. 2) Time in minutes (the value passed here should be between 0 and 60 – if the value is incorrect the results will be incorrect.) Above function can be enhanced by adding functionalities like a) Validation of the parameters passed b) Accepting values like Quarter Hour, Half Hour etc. Here are few sample examples. SELECT dbo.roundtime1('17:29',30) SELECT dbo.roundtime1(GETDATE(),5) SELECT dbo.roundtime1('2012-11-02 07:27:07.000',15) When you run above code, it will return following results. Well, do you have any other way to achieve the same result? If yes, do share it here and I will be glad to share it on blog with due credit. 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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