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

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

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

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

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  • SQL SERVER – Solution – Puzzle – SELECT * vs SELECT COUNT(*)

    - by pinaldave
    Earlier I have published Puzzle Why SELECT * throws an error but SELECT COUNT(*) does not. This question have received many interesting comments. Let us go over few of the answers, which are valid. Before I start the same, let me acknowledge Rob Farley who has not only answered correctly very first but also started interesting conversation in the same thread. The usual question will be what is the right answer. I would like to point to official Microsoft Connect Items which discusses the same. RGarvao https://connect.microsoft.com/SQLServer/feedback/details/671475/select-test-where-exists-select tiberiu utan http://connect.microsoft.com/SQLServer/feedback/details/338532/count-returns-a-value-1 Rob Farley count(*) is about counting rows, not a particular column. It doesn’t even look to see what columns are available, it’ll just count the rows, which in the case of a missing FROM clause, is 1. “select *” is designed to return columns, and therefore barfs if there are none available. Even more odd is this one: select ‘blah’ where exists (select *) You might be surprised at the results… Koushik The engine performs a “Constant scan” for Count(*) where as in the case of “SELECT *” the engine is trying to perform either Index/Cluster/Table scans. amikolaj When you query ‘select * from sometable’, SQL replaces * with the current schema of that table. With out a source for the schema, SQL throws an error. so when you query ‘select count(*)’, you are counting the one row. * is just a constant to SQL here. Check out the execution plan. Like the description states – ‘Scan an internal table of constants.’ You could do ‘select COUNT(‘my name is adam and this is my answer’)’ and get the same answer. Netra Acharya SELECT * Here, * represents all columns from a table. So it always looks for a table (As we know, there should be FROM clause before specifying table name). So, it throws an error whenever this condition is not satisfied. SELECT COUNT(*) Here, COUNT is a Function. So it is not mandetory to provide a table. Check it out this: DECLARE @cnt INT SET @cnt = COUNT(*) SELECT @cnt SET @cnt = COUNT(‘x’) SELECT @cnt Naveen Select 1 / Select ‘*’ will return 1/* as expected. Select Count(1)/Count(*) will return the count of result set of select statement. Count(1)/Count(*) will have one 1/* for each row in the result set of select statement. Select 1 or Select ‘*’ result set will contain only 1 result. so count is 1. Where as “Select *” is a sysntax which expects the table or equauivalent to table (table functions, etc..). It is like compilation error for that query. Ramesh Hi Friends, Count is an aggregate function and it expects the rows (list of records) for a specified single column or whole rows for *. So, when we use ‘select *’ it definitely give and error because ‘*’ is meant to have all the fields but there is not any table and without table it can only raise an error. So, in the case of ‘Select Count(*)’, there will be an error as a record in the count function so you will get the result as ’1'. Try using : Select COUNT(‘RAMESH’) and think there is an error ‘Must specify table to select from.’ in place of ‘RAMESH’ Pinal : If i am wrong then please clarify this. Sachin Nandanwar Any aggregate function expects a constant or a column name as an expression. DO NOT be confused with * in an aggregate function.The aggregate function does not treat it as a column name or a set of column names but a constant value, as * is a key word in SQL. You can replace any value instead of * for the COUNT function.Ex Select COUNT(5) will result as 1. The error resulting from select * is obvious it expects an object where it can extract the result set. I sincerely thank you all for wonderful conversation, I personally enjoyed it and I am sure all of you have the same feeling. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: CodeProject, Pinal Dave, PostADay, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • SQL SERVER – World Shapefile Download and Upload to Database – Spatial Database

    - by pinaldave
    During my recent, training I was asked by a student if I know a place where he can download spatial files for all the countries around the world, as well as if there is a way to upload shape files to a database. Here is a quick tutorial for it. VDS Technologies has all the spatial files for every location for free. You can download the spatial file from here. If you cannot find the spatial file you are looking for, please leave a comment here, and I will send you the necessary details. Unzip the file to a folder and it will have the following content. Then, download Shape2SQL tool from SharpGIS. This is one of the best tools available to convert shapefiles to SQL tables. Afterwards, run the .exe file. When the file is run for the first time, it will ask for the database properties. Provide your database details. Select the appropriate shape files and the tool will fill up the essential details automatically. If you do not want to create the index on the column, uncheck the box beside it. The screenshot below is simply explains the procedure. You also have to be careful regarding your data, whether that is GEOMETRY or GEOGRAPHY. In this example,  it is GEOMETRY data. Click “Upload to Database”. It will show you the uploading process. Once the shape file is uploaded, close the application and open SQL Server Management Studio (SSMS). Run the following code in SSMS Query Editor. USE Spatial GO SELECT * FROM dbo.world GO This will show the complete map of world after you click on Spatial Results in Spatial Tab. In Spatial Results Set, the Zoom feature is available. From the Select label column, choose the country name in order to show the country name overlaying the country borders. Let me know if this tutorial is helpful enough. I am planning to write a few more posts about this later. Note: Please note that the images displayed here do not reflect the original political boundaries. These data are pretty old and can probably draw incorrect maps as well. I have personally spotted several parts of the map where some countries are located a little bit inaccurately. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Add-On, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Spatial, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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  • SQL SERVER – Out of the Box – Activty and Performance Reports from SSSMS

    - by pinaldave
    SQL Server management Studio 2008 is wonderful tool and has many different features. Many times, an average user does not use them as they are not aware about these features. Today, we will learn one such feature. SSMS comes with many inbuilt performance and activity reports, but we do not use it to the full potential. Let us see how we can access these standard reports. Connect to SQL Server Node >> Right Click on it >> Go to Reports >> Click on Standard Reports >> Pick Any Report. Click to Enlarge You can see there are many reports, which an average users needs right away, are available there. Let me list all the reports available. Server Dashboard Configuration Changes History Schema Changes History Scheduler Health Memory Consumption Activity – All Blocking Transactions Activity – All Cursors Activity – All Sessions Activity – Top Sessions Activity – Dormant Sessions Activity -  Top Connections Top Transactions by Age Top Transactions by Blocked Transactions Count Top Transactions by Locks Count Performance – Batch Execution Statistics Performance – Object Execution Statistics Performance – Top Queries by Average CPU Time Performance – Top Queries by Average IO Performance – Top Queries by Total CPU Time Performance – Top Queries by Total IO Service Broker Statistics Transactions Log Shipping Status In fact, when you look at the above list, it is fairly clear that they are very thought out and commonly needed reports that are available in SQL Server 2008. Let us run a couple of reports and observe their result. Performance – Top Queries by Total CPU Time Click to Enlarge Memory Consumption Click to Enlarge There are options for custom reports as well, which we can configure. We will learn about them in some other post. Additionally, you can right click on the reports and export in Excel or PDF. I think this tool can really help those who are just looking for some quick details. Does any of you use this feature, or this feature has some limitations and You would like to see more features? Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Mirroring Configured Without Domain – The server network address TCP://SQLServerName:50

    - by pinaldave
    Regular readers of my blog will be aware of my friend who called me few days ago with very a funny SQL Problem SQL SERVER – SSMS Query Command(s) completed successfully without ANY Results. This time, it did not take long before he called me up with another interesting problem, although the issue he was facing this time was not that interesting and also very specific to him, however, he insisted me to share with all of you. Let us understand his situation at first. My friend is preparing for DBA exam Exam 70-450: PRO: Designing, Optimizing and Maintaining a Database Server Infrastructure using Microsoft SQL Server 2008 and for the same, he was trying to set up replication on his local laptop. He had installed two different instances of SQL Server on his computer and every time when he started the mirroring, it failed with common error message. The server network address “TCP://SQLServer:5023? cannot be reached or does not exist. Check the network address name and that the ports for the local and remote endpoints are operational. (Microsoft SQL Server, Error: 1418) Well, before he contacted me, he searched online and checked my article written on the error in mirroring. However, he tried all the four suggestions, but it did not solve his problem. He called me at a reasonable time of late evening (unlike last time, which was midnight!). I even tried all the seven different suggestions myself, as previously proposed in my article; however, none of them worked. While looking at closely at services, I noticed something very simple. He was running all the instances on ‘Network Services’. In fact, his computer was a stand-alone computer. There was no network at all. Also, there was no domain or any other advance network concepts implemented. I just changed services from ‘Network Services’ to ‘Local System’ as his SQL Server was running on his local system and there were no network services. This prompted to restart the services. As this was not the production server and his development machine, we restarted the services on the laptop (do not restart services on production server without proper planning). After changing the ‘services log on’ account to localsystem, when he attempted to reconfigure the mirroring it worked right away. As usually in production server, proper domains are configured and advance network concepts are implemented I had never faced this type of problem earlier. My friend insisted to post this solution to his situation, wherein there was no domain configured and setting up mirroring was throwing an error. According to him, this is bound to help people, like him, who are preparing for certification using single system. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Certifications, SQL Mirroring

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  • SQL SERVER – Summary of Month – Wait Type – Day 28 of 28

    - by pinaldave
    I am glad to announce that the month of Wait Types and Queues very successful. I am glad that it was very well received and there was great amount of participation from community. I am fortunate to have some of the excellent comments throughout the series. I want to dedicate this series to all the guest blogger – Jonathan, Jacob, Glenn, and Feodor for their kindness to take a participation in this series. Here is the complete list of the blog posts in this series. I enjoyed writing the series and I plan to continue writing similar series. Please offer your opinion. SQL SERVER – Introduction to Wait Stats and Wait Types – Wait Type – Day 1 of 28 SQL SERVER – Signal Wait Time Introduction with Simple Example – Wait Type – Day 2 of 28 SQL SERVER – DMV – sys.dm_os_wait_stats Explanation – Wait Type – Day 3 of 28 SQL SERVER – DMV – sys.dm_os_waiting_tasks and sys.dm_exec_requests – Wait Type – Day 4 of 28 SQL SERVER – Capturing Wait Types and Wait Stats Information at Interval – Wait Type – Day 5 of 28 SQL SERVER – CXPACKET – Parallelism – Usual Solution – Wait Type – Day 6 of 28 SQL SERVER – CXPACKET – Parallelism – Advanced Solution – Wait Type – Day 7 of 28 SQL SERVER – SOS_SCHEDULER_YIELD – Wait Type – Day 8 of 28 SQL SERVER – PAGEIOLATCH_DT, PAGEIOLATCH_EX, PAGEIOLATCH_KP, PAGEIOLATCH_SH, PAGEIOLATCH_UP – Wait Type – Day 9 of 28 SQL SERVER – IO_COMPLETION – Wait Type – Day 10 of 28 SQL SERVER – ASYNC_IO_COMPLETION – Wait Type – Day 11 of 28 SQL SERVER – PAGELATCH_DT, PAGELATCH_EX, PAGELATCH_KP, PAGELATCH_SH, PAGELATCH_UP – Wait Type – Day 12 of 28 SQL SERVER – FT_IFTS_SCHEDULER_IDLE_WAIT – Full Text – Wait Type – Day 13 of 28 SQL SERVER – BACKUPIO, BACKUPBUFFER – Wait Type – Day 14 of 28 SQL SERVER – LCK_M_XXX – Wait Type – Day 15 of 28 SQL SERVER – Guest Post – Jonathan Kehayias – Wait Type – Day 16 of 28 SQL SERVER – WRITELOG – Wait Type – Day 17 of 28 SQL SERVER – LOGBUFFER – Wait Type – Day 18 of 28 SQL SERVER – PREEMPTIVE and Non-PREEMPTIVE – Wait Type – Day 19 of 28 SQL SERVER – MSQL_XP – Wait Type – Day 20 of 28 SQL SERVER – Guest Posts – Feodor Georgiev – The Context of Our Database Environment – Going Beyond the Internal SQL Server Waits – Wait Type – Day 21 of 28 SQL SERVER – Guest Post – Jacob Sebastian – Filestream – Wait Types – Wait Queues – Day 22 of 28 SQL SERVER – OLEDB – Link Server – Wait Type – Day 23 of 28 SQL SERVER – 2000 – DBCC SQLPERF(waitstats) – Wait Type – Day 24 of 28 SQL SERVER – 2011 – Wait Type – Day 25 of 28 SQL SERVER – Guest Post – Glenn Berry – Wait Type – Day 26 of 28 SQL SERVER – Best Reference – Wait Type – Day 27 of 28 SQL SERVER – Summary of Month – Wait Type – Day 28 of 28 Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Optimization, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, SQLServer, T SQL, Technology

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  • SQL SERVER – Remove Debug Button in SSMS – SQL in Sixty Seconds #020 – Video

    - by pinaldave
    SQL in Sixty Seconds is indeed tremendous fun to do. Every week, we try to come up with some new learning which we can share in Sixty Seconds. In this busy world, we all have sixty seconds to learn something new – no matter how much busy we are. In this episode of the series, we talk about another interesting feature of SQL Server Management Studio. In SQL Server Management Studio (SSMS) we have two button side by side. 1) Execute (!) and 2) Debug (>). It is quite confusing to a few developers. The debug button which looks like a play button encourages developers to click on the same thinking it will execute the code. Also developer with a Visual Studio background often click it because of their habit. However, Debug button is not the same as Execute button. In most of the cases developers want to click on Execute to run the query but by mistake they click on Debug and it wastes their valuable time. It is very easy to fix this. If developers are not frequently using a debug feature in SQL Server they should hide it from the toolbar itself. This will reduce the chances to incorrectly click on the debug button greatly as well save lots of time for developer as invoking debug processes and turning it off takes a few extra moments. In this Sixty second video we will discuss how one can hide the debug button and avoid confusion regarding execution button. I personally use function key F5 to execute the T-SQL code so I do not face this problem that often. More on Removing Debug Button in SSMS: SQL SERVER – Read Only Files and SQL Server Management Studio (SSMS) SQL SERVER – Standard Reports from SQL Server Management Studio – SQL in Sixty Seconds #016 – Video SQL SERVER – Discard Results After Query Execution – SSMS SQL SERVER – Tricks to Comment T-SQL in SSMS – SQL in Sixty Seconds #019 – Video SQL SERVER – Right Aligning Numerics in SQL Server Management Studio (SSMS) 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 – Copy Data from One Table to Another Table – SQL in Sixty Seconds #031 – Video

    - by pinaldave
    Copy data from one table to another table is one of the most requested questions on forums, Facebook and Twitter. The question has come in many formats and there are places I have seen developers are using cursor instead of this direct method. Earlier I have written the similar article a few years ago - SQL SERVER – Insert Data From One Table to Another Table – INSERT INTO SELECT – SELECT INTO TABLE. The article has been very popular and I have received many interesting and constructive comments. However there were two specific comments keep on ending up on my mailbox. 1) SQL Server AdventureWorks Samples Database does not have table I used in the example 2) If there is a video tutorial of the same example. After carefully thinking I decided to build a new set of the scripts for the example which are very similar to the old one as well video tutorial of the same. There was no better place than our SQL in Sixty Second Series to cover this interesting small concept. Let me know what you think of this video. Here is the updated script. -- Method 1 : INSERT INTO SELECT USE AdventureWorks2012 GO ----Create TestTable CREATE TABLE TestTable (FirstName VARCHAR(100), LastName VARCHAR(100)) ----INSERT INTO TestTable using SELECT INSERT INTO TestTable (FirstName, LastName) SELECT FirstName, LastName FROM Person.Person WHERE EmailPromotion = 2 ----Verify that Data in TestTable SELECT FirstName, LastName FROM TestTable ----Clean Up Database DROP TABLE TestTable GO --------------------------------------------------------- --------------------------------------------------------- -- Method 2 : SELECT INTO USE AdventureWorks2012 GO ----Create new table and insert into table using SELECT INSERT SELECT FirstName, LastName INTO TestTable FROM Person.Person WHERE EmailPromotion = 2 ----Verify that Data in TestTable SELECT FirstName, LastName FROM TestTable ----Clean Up Database DROP TABLE TestTable GO Related Tips in SQL in Sixty Seconds: SQL SERVER – Insert Data From One Table to Another Table – INSERT INTO SELECT – SELECT INTO TABLE Powershell – Importing CSV File Into Database – Video SQL SERVER – 2005 – Export Data From SQL Server 2005 to Microsoft Excel Datasheet SQL SERVER – Import CSV File into Database Table Using SSIS SQL SERVER – Import CSV File Into SQL Server Using Bulk Insert – Load Comma Delimited File Into SQL Server SQL SERVER – 2005 – Generate Script with Data from Database – Database Publishing Wizard 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 – What is MDS? – Master Data Services in Microsoft SQL Server 2008 R2

    - by pinaldave
    What is MDS? Master Data Services helps enterprises standardize the data people rely on to make critical business decisions. With Master Data Services, IT organizations can centrally manage critical data assets company wide and across diverse systems, enable more people to securely manage master data directly, and ensure the integrity of information over time. (Source: Microsoft) Today I will be talking about the same subject at Microsoft TechEd India. If you want to learn about how to standardize your data and apply the business rules to validate data you must attend my session. MDS is very interesting concept, I will cover super short but very interesting 10 quick slides about this subject. I will make sure in very first 20 mins, you will understand following topics Introduction to Master Data Management What is Master Data and Challenges MDM Challenges and Advantage Microsoft Master Data Services Benefits and Key Features Uses of MDS Capabilities Key Features of MDS This slides decks will be followed by around 30 mins demo which will have story of entity, hierarchies, versions, security, consolidation and collection. I will be tell this story keeping business rules in center. We take one business rule which will be simple validation rule and will make it much more complex and yet very useful to product. I will also demonstrate few real life scenario where I will be talking about MDS and its usage. Do not miss this session. At the end of session there will be book awarded to best participant. My session details: Session: Master Data Services in Microsoft SQL Server 2008 R2 Date: April 12, 2010  Time: 2:30pm-3:30pm SQL Server Master Data Services will ship with SQL Server 2008 R2 and will improve Microsoft’s platform appeal. This session provides an in depth demonstration of MDS features and highlights important usage scenarios. Master Data Services enables consistent decision making by allowing you to create, manage and propagate changes from single master view of your business entities. Also with MDS – Master Data-hub which is the vital component helps ensure reporting consistency across systems and deliver faster more accurate results across the enterprise. We will talk about establishing the basis for a centralized approach to defining, deploying, and managing master data in the enterprise. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Business Intelligence, Data Warehousing, MVP, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL, Technology Tagged: TechEd, TechEdIn

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  • SQL SERVER – Understanding ALTER INDEX ALL REBUILD with Disabled Clustered Index

    - by pinaldave
    This blog is in response to the ongoing communication with the reader who had earlier asked the question of SQL SERVER – Disable Clustered Index and Data Insert. The same reader has asked me the difference between ALTER INDEX ALL REBUILD and ALTER INDEX REBUILD along with disabled clustered index. Instead of writing a big theory, we will go over the demo right away. Here are the steps that we intend to follow. 1) Create Clustered and Nonclustered Index 2) Disable Clustered and Nonclustered Index 3) Enable – a) All Indexes, b) Clustered Index USE tempdb GO -- Drop Table if Exists IF EXISTS (SELECT * FROM sys.objects WHERE OBJECT_ID = OBJECT_ID(N'[dbo].[TableName]') AND type IN (N'U')) DROP TABLE [dbo].[TableName] GO -- Create Table CREATE TABLE [dbo].[TableName]( [ID] [int] NOT NULL, [FirstCol] [varchar](50) NULL ) GO -- Create Clustered Index ALTER TABLE [TableName] ADD CONSTRAINT [PK_TableName] PRIMARY KEY CLUSTERED ([ID] ASC) GO -- Create Nonclustered Index CREATE UNIQUE NONCLUSTERED INDEX [IX_NonClustered_TableName] ON [dbo].[TableName] ([FirstCol] ASC) GO -- Check that all the indexes are enabled SELECT OBJECT_NAME(OBJECT_ID), Name, type_desc, is_disabled FROM sys.indexes WHERE OBJECT_NAME(OBJECT_ID) = 'TableName' GO Now let us disable both the indexes. -- Disable Indexes -- Disable Nonclustered Index ALTER INDEX [IX_NonClustered_TableName] ON [dbo].[TableName] DISABLE GO -- Disable Clustered Index ALTER INDEX [PK_TableName] ON [dbo].[TableName] DISABLE GO -- Check that all the indexes are disabled SELECT OBJECT_NAME(OBJECT_ID), Name, type_desc, is_disabled FROM sys.indexes WHERE OBJECT_NAME(OBJECT_ID) = 'TableName' GO Next, let us rebuild all the indexes and see the output. -- Test 1: ALTER INDEX ALL REBUILD -- Rebuliding should work fine ALTER INDEX ALL ON [dbo].[TableName] REBUILD GO -- Check that all the indexes are enabled SELECT OBJECT_NAME(OBJECT_ID), Name, type_desc, is_disabled FROM sys.indexes WHERE OBJECT_NAME(OBJECT_ID) = 'TableName' GO Now, once again disable indexes for the second test. -- Disable Indexes -- Disable Nonclustered Index ALTER INDEX [IX_NonClustered_TableName] ON [dbo].[TableName] DISABLE GO -- Disable Clustered Index ALTER INDEX [PK_TableName] ON [dbo].[TableName] DISABLE GO -- Check that all the indexes are disabled SELECT OBJECT_NAME(OBJECT_ID), Name, type_desc, is_disabled FROM sys.indexes WHERE OBJECT_NAME(OBJECT_ID) = 'TableName' GO Next, let us build only the clustered index and see the output of all the indexes. -- Test 2: ALTER INDEX REBUILD -- Rebuliding should work fine ALTER INDEX [PK_TableName] ON [dbo].[TableName] REBUILD GO -- Check that only clustered index is enabled SELECT OBJECT_NAME(OBJECT_ID), Name, type_desc, is_disabled FROM sys.indexes WHERE OBJECT_NAME(OBJECT_ID) = 'TableName' GO Let us do final clean up. -- Clean up DROP TABLE [TableName] GO From the example, it is very clear that if you have built only clustered index when the nonclustered index is disabled, it still remains disabled. Do let me know if the idea is clear. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Index, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Difference Between DATETIME and DATETIME2

    - by pinaldave
    Yesterday I have written a very quick blog post on SQL SERVER – Difference Between GETDATE and SYSDATETIME and I got tremendous response for the same. I suggest you read that blog post before continuing this blog post today. I had asked people to honestly take part and share their view about above two system function. There are few emails as well few comments on the blog post asking question how did I come to know the difference between the same. The answer is real world issues. I was called in for performance tuning consultancy where I was asked very strange question by one developer. Here is the situation he was facing. System had a single table with two different column of datetime. One column was datelastmodified and second column was datefirstmodified. One of the column was DATETIME and another was DATETIME2. Developer was populating them with SYSDATETIME respectively. He was always thinking that the value inserted in the table will be the same. This table was only accessed by INSERT statement and there was no updates done over it in application.One fine day he ran distinct on both of this column and was in for surprise. He always thought that both of the table will have same data, but in fact they had very different data. He presented this scenario to me. I said this can not be possible but when looked at the resultset, I had to agree with him. Here is the simple script generated to demonstrate the problem he was facing. This is just a sample of original table. DECLARE @Intveral INT SET @Intveral = 10000 CREATE TABLE #TimeTable (FirstDate DATETIME, LastDate DATETIME2) WHILE (@Intveral > 0) BEGIN INSERT #TimeTable (FirstDate, LastDate) VALUES (SYSDATETIME(), SYSDATETIME()) SET @Intveral = @Intveral - 1 END GO SELECT COUNT(DISTINCT FirstDate) D_GETDATE, COUNT(DISTINCT LastDate) D_SYSGETDATE FROM #TimeTable GO SELECT DISTINCT a.FirstDate, b.LastDate FROM #TimeTable a INNER JOIN #TimeTable b ON a.FirstDate = b.LastDate GO SELECT * FROM #TimeTable GO DROP TABLE #TimeTable GO Let us see the resultset. You can clearly see from result that SYSDATETIME() does not populate the same value in the both of the field. In fact the value is either rounded down or rounded up in the field which is DATETIME. Event though we are populating the same value, the values are totally different in both the column resulting the SELF JOIN fail and display different DISTINCT values. The best policy is if you are using DATETIME use GETDATE() and if you are suing DATETIME2 use SYSDATETIME() to populate them with current date and time to accurately address the precision. As DATETIME2 is introduced in SQL Server 2008, above script will only work with SQL SErver 2008 and later versions. I hope I have answered few questions asked yesterday. Reference: Pinal Dave (http://www.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL DateTime, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – Milestone of 1300th Post and A Few Updates

    - by pinaldave
    Today is my 1300th blog post and I realize that my blog has been quite running such a long journey. I have been writing for a lengthy time on this tech blog. Today I would like to go back and briefly recall the posts that were part of my blog’s history. Read all list of all my blog posts here. This blog only started as a list of personal bookmarks. I used to just write down scripts on the blog for my personal use. I was the one who wrote many scripts here for the servers that I was maintaining to keep them polished. I have included many links in my first blog posts which I view as just a collection of bookmarks on my very own blog; no intentions of publishing other contents besides the scripts, at all. Gradually, I realized that people read my blog and follow the advices which were supposedly meant only for me. I tried to write a code and a script which are generic in nature, so anyone can just use it right away. Nothing is perfect. When I was writing the last 1299 posts (and having 14 Million+ views), I have made a few mistakes and tweaks that I thoughtfully accepted. These are corrections that were pointed out by many kind souls and readers like you, which have helped me develop wonderful blogging experiences. I am very glad that I have this blog wherein I can express myself. After all, I would have not reached where I am today if I have kept myself worried in terms of expressing my knowledge and understanding SQL Server. I am happy that many of you appreciated my efforts and supported me all the way, which also helped me achieve where I am now. I promise to learn more about this fascinating subject and, of course, continue to share whatever I will learn to my dear readers. Again, I really thank YOU for reading this blog and supporting the SQL community. Reference: Pinal Dave (http://blog.SQLAuthority.com), Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: SQL Milestone

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  • SQL SERVER – WRITELOG – Wait Type – Day 17 of 28

    - by pinaldave
    WRITELOG is one of the most interesting wait types. So far we have seen a lot of different wait types, but this log type is associated with log file which makes it interesting to deal with. From Book On-Line: WRITELOG Occurs while waiting for a log flush to complete. Common operations that cause log flushes are checkpoints and transaction commits. WRITELOG Explanation: This wait type is usually seen in the heavy transactional database. When data is modified, it is written both on the log cache and buffer cache. This wait type occurs when data in the log cache is flushing to the disk. During this time, the session has to wait due to WRITELOG. I have recently seen this wait type’s persistence at my client’s place, where one of the long-running transactions was stopped by the user causing it to roll back. In the future, I will see if I could re-create this situation once again on my machine to validate the relation. Reducing WRITELOG wait: There are several suggestions to reduce this wait stats: Move Transaction Log to Separate Disk from mdf and other files. Avoid cursor-like coding methodology and frequent committing of statements. Find the most active file based on IO stall time based on 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. There are two excellent resources by Paul Randal, I suggest you understand the subject from those videos. The links to videos are here and here. 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 – Stored Procedure and Transactions

    - by pinaldave
    I just overheard the following statement – “I do not use Transactions in SQL as I use Stored Procedure“. I just realized that there are so many misconceptions about this subject. Transactions has nothing to do with Stored Procedures. Let me demonstrate that with a simple example. USE tempdb GO -- Create 3 Test Tables CREATE TABLE TABLE1 (ID INT); CREATE TABLE TABLE2 (ID INT); CREATE TABLE TABLE3 (ID INT); GO -- Create SP CREATE PROCEDURE TestSP AS INSERT INTO TABLE1 (ID) VALUES (1) INSERT INTO TABLE2 (ID) VALUES ('a') INSERT INTO TABLE3 (ID) VALUES (3) GO -- Execute SP -- SP will error out EXEC TestSP GO -- Check the Values in Table SELECT * FROM TABLE1; SELECT * FROM TABLE2; SELECT * FROM TABLE3; GO Now, the main point is: If Stored Procedure is transactional then, it should roll back complete transactions when it encounters any errors. Well, that does not happen in this case, which proves that Stored Procedure does not only provide just the transactional feature to a batch of T-SQL. Let’s see the result very quickly. It is very clear that there were entries in table1 which are not shown in the subsequent tables. If SP was transactional in terms of T-SQL Query Batches, there would be no entries in any of the tables. If you want to use Transactions with Stored Procedure, wrap the code around with BEGIN TRAN and COMMIT TRAN. The example is as following. CREATE PROCEDURE TestSPTran AS BEGIN TRAN INSERT INTO TABLE1 (ID) VALUES (11) INSERT INTO TABLE2 (ID) VALUES ('b') INSERT INTO TABLE3 (ID) VALUES (33) COMMIT GO -- Execute SP EXEC TestSPTran GO -- Check the Values in Tables SELECT * FROM TABLE1; SELECT * FROM TABLE2; SELECT * FROM TABLE3; GO -- Clean up DROP TABLE Table1 DROP TABLE Table2 DROP TABLE Table3 GO In this case, there will be no entries in any part of the table. What is your opinion about this blog post? Please leave your comments about it here. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Stored Procedure, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – When are Statistics Updated – What triggers Statistics to Update

    - by pinaldave
    If you are an SQL Server Consultant/Trainer involved with Performance Tuning and Query Optimization, I am sure you have faced the following questions many times. When is statistics updated? What is the interval of Statistics update? What is the algorithm behind update statistics? These are the puzzling questions and more. I searched the Internet as well many official MS documents in order to find answers. All of them have provided almost similar algorithm. However, at many places, I have seen a bit of variation in algorithm as well. I have finally compiled the list of various algorithms and decided to share what was the most common “factor” in all of them. I would like to ask for your suggestions as whether following the details, when Statistics is updated, are accurate or not. I will update this blog post with accurate information after receiving your ideas. The answer I have found here is when statistics are expired and not when they are automatically updated. I need your help here to answer when they are updated. Permanent table If the table has no rows, statistics is updated when there is a single change in table. If the number of rows in a table is less than 500, statistics is updated for every 500 changes in table. If the number of rows in table is more than 500, statistics is updated for every 500+20% of rows changes in table. Temporary table If the table has no rows, statistics is updated when there is a single change in table. If the number of rows in table is less than 6, statistics is updated for every 6 changes in table. If the number of rows in table is less than 500, statistics is updated for every 500 changes in table. If the number of rows in table is more than 500, statistics is updated for every 500+20% of rows changes in table. Table variable There is no statistics for Table Variables. If you want to read further about statistics, I suggest that you read the white paper Statistics Used by the Query Optimizer in Microsoft SQL Server 2008. Let me know your opinions about statistics, as well as if there is any update in the above algorithm. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, Readers Question, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Statistics

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  • SQLAuthority News – Monthly Roundup of Best SQL Posts

    - by pinaldave
    After receiving lots of requests from different readers for long time I have decided to write first monthly round up. If all of you like it I will continue writing the same every month. In fact, I really like the idea as I was able to go back and read all of my posts written in this month. This month was started with answering one of the most common question asked me to about What is Adventureworks? Many of you know the answer but to the surprise more number of the reader did not know the answer. There were few extra blog post which were in the same line as following. SQL SERVER – The Difference between Dual Core vs. Core 2 Duo SQLAuthority News – Wireless Router Security and Attached Devices – Complex Password SQL SERVER – DATE and TIME in SQL Server 2008 DMVs are also one of the most handy tools available in SQL Server, I have written following blog post where I have used DMV in scripts. SQL SERVER – Get Latest SQL Query for Sessions – DMV SQL SERVER – Find Most Expensive Queries Using DMV SQL SERVER – List All the DMV and DMF on Server I was able to write two follow-up of my earlier series where I was finding the size of the indexes using different SQL Scripts. And in fact one of the article Powershell is used as well. This was my very first attempt to use Powershell. SQL SERVER – Size of Index Table for Each Index – Solution 2 SQL SERVER – Size of Index Table for Each Index – Solution 3 – Powershell SQL SERVER – Four Posts on Removing the Bookmark Lookup – Key Lookup Without realizing I wrote series of the blog post on disabled index here is its complete list. I plan to write one more follow-up list on the same. SQL SERVER – Disable Clustered Index and Data Insert SQL SERVER – Understanding ALTER INDEX ALL REBUILD with Disabled Clustered Index SQL SERVER – Disabled Index and Update Statistics Two special post which I found very interesting to write are as following. SQL SERVER – SHRINKFILE and TRUNCATE Log File in SQL Server 2008 SQL SERVER – Simple Example of Snapshot Isolation – Reduce the Blocking Transactions In personal adventures, I won the Community Impact Award for Last Year from Microsoft. Please leave your comment about how can I improve this round up or what more details I should include in the same. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – FT_IFTS_SCHEDULER_IDLE_WAIT – Full Text – Wait Type – Day 13 of 28

    - by pinaldave
    In the last few days during this series, I got many question about this Wait type. It would be great if you read my original related wait stats query in the first post because I have filtered it out in WHERE clause. However, I still get questions about this being one of the most wait types they encounter. The truth is, this is a background task processing and it really does not matter and it should be filtered out. There are many new Wait types related to Full Text Search that are introduced in SQL Server 2008. If you run the following query, you will be able to find them in the list. Currently there is not enough information for all of them available on BOL or any other place. But don’t worry; I will write an in-depth article when I learn more about them. SELECT * FROM sys.dm_os_wait_stats WHERE wait_type LIKE 'FT_%' The result set will contain following rows. FT_RESTART_CRAWL FT_METADATA_MUTEX FT_IFTSHC_MUTEX FT_IFTSISM_MUTEX FT_IFTS_RWLOCK FT_COMPROWSET_RWLOCK FT_MASTER_MERGE FT_IFTS_SCHEDULER_IDLE_WAIT We have understood so far that there is not much information available. But the problem is when you have this Wait type, what should you do?  The answer is to filter them out for the moment (i.e, do not pay attention on them) and focus on other pressing issues in wait stats or performance tuning. Here are two of my informal suggestions, which are totally independent from wait stats: Turn off the Full Text Search service in your system if you are  not necessarily using it on your server. Learn proper Full Text Search methodology. You can get Michael Coles’ book: Pro Full-Text Search in SQL Server 2008. Now I invite you to speak out your suggestions or any input regarding Full Text-related best practices and wait stats issue. Please leave a comment. 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 discussions of Wait Stats in this blog are generic and vary 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 – What the Business Says Is Not What the Business Wants

    - by pinaldave
    This blog post is written in response to T-SQL Tuesday hosted by Steve Jones. Steve raised a very interesting question; every DBA and Database Developer has already faced this situation. When I read the topic, I felt that I can write several different examples here. Today, I will cover this scenario, which seems quite amusing. Shrinking Database Earlier this year, I was working on SQL Server Performance Tuning consultancy; I had faced very interesting situation. No matter how much I attempt to reduce the fragmentation, I always end up with heavy fragmentation on the server. After careful research, I figured out that one of the jobs was continuously Shrinking the Database – which is a very bad practice. I have blogged about my experience over here SQL SERVER – SHRINKDATABASE For Every Database in the SQL Server. I removed the incorrect shrinking process right away; once it was removed, everything continued working as it should be. After a couple of days, I learned that one of their DBAs had put back the same DBCC process. I requested the Senior DBA to find out what is going on and he came up with the following reason: “Business Requirement.” I cannot believe this! Now, it was time for me to go deep into the subject. Moreover, it had become necessary to understand the need. After talking to the concerned people here, I understood what they needed. Please read the exact business need in their own language. The Shrinking “Business Need” “We shrink the database because if we take backup after shrinking the database, the size of the same is smaller. Once we take backup, we have to send it to our remote location site. Our business requirement is that we need to always make sure that the file is smallest when we transfer it to remote server.” The backup is not affected in any way if you shrink the database or not. The size of backup will be the same. After a couple of the tests, they agreed with me. Shrinking will create performance issues for the same as it will introduce heavy fragmentation in the database. The Real Solution The real business need was that they needed the smallest possible backup file. We finally implemented a quick solution which they are still using to date. The solution was compressed backup. I have written about this subject in detail few years before SQL SERVER – 2008 – Introduction to New Feature of Backup Compression. Compressed backup not only creates a small filesize but also increases the speed of the database as well. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Best Practices, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • SQL SERVER – Introduction to Adaptive ETL Tool – How adaptive is your ETL?

    - by pinaldave
    I am often reminded by the fact that BI/data warehousing infrastructure is very brittle and not very adaptive to change. There are lots of basic use cases where data needs to be frequently loaded into SQL Server or another database. What I have found is that as long as the sources and targets stay the same, SSIS or any other ETL tool for that matter does a pretty good job handling these types of scenarios. But what happens when you are faced with more challenging scenarios, where the data formats and possibly the data types of the source data are changing from customer to customer?  Let’s examine a real life situation where a health management company receives claims data from their customers in various source formats. Even though this company supplied all their customers with the same claims forms, they ended up building one-off ETL applications to process the claims for each customer. Why, you ask? Well, it turned out that the claims data from various regional hospitals they needed to process had slightly different data formats, e.g. “integer” versus “string” data field definitions.  Moreover the data itself was represented with slight nuances, e.g. “0001124” or “1124” or “0000001124” to represent a particular account number, which forced them, as I eluded above, to build new ETL processes for each customer in order to overcome the inconsistencies in the various claims forms.  As a result, they experienced a lot of redundancy in these ETL processes and recognized quickly that their system would become more difficult to maintain over time. So imagine for a moment that you could use an ETL tool that helps you abstract the data formats so that your ETL transformation process becomes more reusable. Imagine that one claims form represents a data item as a string – acc_no(varchar) – while a second claims form represents the same data item as an integer – account_no(integer). This would break your traditional ETL process as the data mappings are hard-wired.  But in a world of abstracted definitions, all you need to do is create parallel data mappings to a common data representation used within your ETL application; that is, map both external data fields to a common attribute whose name and type remain unchanged within the application. acc_no(varchar) is mapped to account_number(integer) expressor Studio first claim form schema mapping account_no(integer) is also mapped to account_number(integer) expressor Studio second claim form schema mapping All the data processing logic that follows manipulates the data as an integer value named account_number. Well, these are the kind of problems that that the expressor data integration solution automates for you.  I’ve been following them since last year and encourage you to check them out by downloading their free expressor Studio ETL software. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Business Intelligence, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: ETL, SSIS

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  • SQL SERVER – Index Created on View not Used Often – Observation of the View – Part 2

    - by pinaldave
    Earlier, I have written an article about SQL SERVER – Index Created on View not Used Often – Observation of the View. I received an email from one of the readers, asking if there would no problems when we create the Index on the base table. Well, we need to discuss this situation in two different cases. Before proceeding to the discussion, I strongly suggest you read my earlier articles. To avoid the duplication, I am not going to repeat the code and explanation over here. In all the earlier cases, I have explained in detail how Index created on the View is not utilized. SQL SERVER – Index Created on View not Used Often – Limitation of the View 12 SQL SERVER – Index Created on View not Used Often – Observation of the View SQL SERVER – Indexed View always Use Index on Table As per earlier blog posts, so far we have done the following: Create a Table Create a View Create Index On View Write SELECT with ORDER BY on View However, the blog reader who emailed me suggests the extension of the said logic, which is as follows: Create a Table Create a View Create Index On View Write SELECT with ORDER BY on View Create Index on the Base Table Write SELECT with ORDER BY on View After doing the last two steps, the question is “Will the query on the View utilize the Index on the View, or will it still use the Index of the base table?“ Let us first run the Create example. USE tempdb GO IF EXISTS (SELECT * FROM sys.views WHERE OBJECT_ID = OBJECT_ID(N'[dbo].[SampleView]')) DROP VIEW [dbo].[SampleView] GO IF EXISTS (SELECT * FROM sys.objects WHERE OBJECT_ID = OBJECT_ID(N'[dbo].[mySampleTable]') AND TYPE IN (N'U')) DROP TABLE [dbo].[mySampleTable] GO -- Create SampleTable CREATE TABLE mySampleTable (ID1 INT, ID2 INT, SomeData VARCHAR(100)) INSERT INTO mySampleTable (ID1,ID2,SomeData) SELECT TOP 100000 ROW_NUMBER() OVER (ORDER BY o1.name), ROW_NUMBER() OVER (ORDER BY o2.name), o2.name FROM sys.all_objects o1 CROSS JOIN sys.all_objects o2 GO -- Create View CREATE VIEW SampleView WITH SCHEMABINDING AS SELECT ID1,ID2,SomeData FROM dbo.mySampleTable GO -- Create Index on View CREATE UNIQUE CLUSTERED INDEX [IX_ViewSample] ON [dbo].[SampleView] ( ID2 ASC ) GO -- Select from view SELECT ID1,ID2,SomeData FROM SampleView ORDER BY ID2 GO -- Create Index on Original Table -- On Column ID1 CREATE UNIQUE CLUSTERED INDEX [IX_OriginalTable] ON mySampleTable ( ID1 ASC ) GO -- On Column ID2 CREATE UNIQUE NONCLUSTERED INDEX [IX_OriginalTable_ID2] ON mySampleTable ( ID2 ) GO -- Select from view SELECT ID1,ID2,SomeData FROM SampleView ORDER BY ID2 GO Now let us see the execution plans for both of the SELECT statement. Before Index on Base Table (with Index on View): After Index on Base Table (with Index on View): Looking at both executions, it is very clear that with or without, the View is using Indexes. Alright, I have written 11 disadvantages of the Views. Now I have written one case where the View is using Indexes. Anybody who says that I am being harsh on Views can say now that I found one place where Index on View can be helpful. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL View, SQLServer, T SQL, Technology

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  • SQL SERVER – Automated Type Conversion using Expressor Studio

    - by pinaldave
    Recently I had an interesting situation during my consultation project. Let me share to you how I solved the problem using Expressor Studio. Consider a situation in which you need to read a field, such as customer_identifier, from a text file and pass that field into a database table. In the source file’s metadata structure, customer_identifier is described as a string; however, in the target database table, customer_identifier is described as an integer. Legitimately, all the source values for customer_identifier are valid numbers, such as “109380”. To implement this in an ETL application, you probably would have hard-coded a type conversion function call, such as: output.customer_identifier=stringToInteger(input.customer_identifier) That wasn’t so bad, was it? For this instance, programming this hard-coded type conversion function call was relatively easy. However, hard-coding, whether type conversion code or other business rule code, almost always means that the application containing hard-coded fields, function calls, and values is: a) specific to an instance of use; b) is difficult to adapt to new situations; and c) doesn’t contain many reusable sub-parts. Therefore, in the long run, applications with hard-coded type conversion function calls don’t scale well. In addition, they increase the overall level of effort and degree of difficulty to write and maintain the ETL applications. To get around the trappings of hard-coding type conversion function calls, developers need an access to smarter typing systems. Expressor Studio product offers this feature exactly, by providing developers with a type conversion automation engine based on type abstraction. The theory behind the engine is quite simple. A user specifies abstract data fields in the engine, and then writes applications against the abstractions (whereas in most ETL software, developers develop applications against the physical model). When a Studio-built application is run, Studio’s engine automatically converts the source type to the abstracted data field’s type and converts the abstracted data field’s type to the target type. The engine can do this because it has a couple of built-in rules for type conversions. So, using the example above, a developer could specify customer_identifier as an abstract data field with a type of integer when using Expressor Studio. Upon reading the string value from the text file, Studio’s type conversion engine automatically converts the source field from the type specified in the source’s metadata structure to the abstract field’s type. At the time of writing the data value to the target database, the engine doesn’t have any work to do because the abstract data type and the target data type are just the same. Had they been different, the engine would have automatically provided the conversion. ?Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Database, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: SSIS

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  • SQLAuthority News – Book Review – Beginning T-SQL 2008 by Kathi Kellenberger

    - by pinaldave
    Beginning T-SQL 2008 by Kathi Kellenberger Amazon Link Detail Review: Beginning T-SQL 2008 is one of the best books on the market if you are just beginning to work with Microsoft SQL, or have a little bit of experience and need to learn more quickly. Each chapter of the book introduces a new subject, and builds upon topics covered in previous chapters.  The author of the book, Kathi Kellenberger understands that you need to form a solid foundation of knowledge before moving on to new topics, and sets up each subject nicely.  Because the chapters move in an orderly progression, you continue to use skills you learned earlier. One of the best features of Beginning T-SQL 2008 is that each chapter has multiple examples and exercises.  Many books introduce a topic and then never go back to it.  This book gives enough examples that you will be familiar with the subject when you come across it in real life.  The exercises at the end of the chapter mean that you will be using the skills you learned – and there is no better way to cement a subject in your brain. The book also includes discussions of the common errors that programmers will come across, how to avoid them, and how to fix them if they happen.  Ms. Kellenberger understands that not only do mistakes happen, but they are bound to happen if you aren’t trained properly.  Mistakes are part of the learning process! The book begins by discussions relational theory, so that programmers will understand the way T-SQL works from the ground up.  It also walks readers through writing accurate queries, combining set-based and procedural processing, embedding logic in stored functions, and so much more. Overall, the main goal of Beginning T-SQL 2008 is to introduce novices to SQL programming, and quickly familiarize them with the basics of running the program.  The book is written with the idea that readers will not know any of the technical terms or vocabulary.  However, if you are a little more familiar with SQL and looking to become better, you will still find this book very helpful. Ratting: 4.5+ Stars Summary: I must recommend Beginning T-SQL 2008 highly enough.  If you are going to buy any beginners guide to Transect-SQL, this is the one you should spend your money on.  You can save yourself a lot of time and effort later by using this very affordable manual to learn the basics, which will allow you to become an expert much faster. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Book Review, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – 4 Tips for ETL Software IDE Developers

    - by pinaldave
    In a previous blog, I introduced the notion of Semantic Types. To an end-user, a seamlessly integrated semantic typing engine significantly increases the ease of use of an ETL IDE (integrated development environment, or developer studio). This led me to think about other ease-of-use issues I have encountered while building ETL applications. When I get stumped while programming, I find myself asking the variations on these questions: “How do I…?” “Now what?” “Why isn’t this working?” “Why do I have to redo the work I just did?” It seems to me that a good ETL IDE will anticipate these questions and seek to answer them before they are even asked. So here are my tips to help software vendors build developer IDEs that actually make development easier. How do I…? While developing an ETL application, have you ever asked yourself: “How do I set up the connection to my SQL Server database?”,“How do I import my table definitions from Access?”, etc. An easy answer might be “read the manual” but sometimes product manuals are not robust or easily accessible. So, integrating robust how-to instructions directly into your ETLstudio would help users get the information they need at the time they need it. Now what? IDEs in general know where you last clicked or performed an action using an input device such as a keyboard; so they should be able to reasonably predict the design context you are in and suggest the next steps accordingly. Context-sensitive suggestions based on the state of the user’s work will help users move forward in ETL application development. Why isn’t this working? Or why do I have to wait till I compile to be told about a critical design issue? If an ETL IDE is smart enough to signal to users what in their design structures is left to be completed or has been completed incorrectly, then the developer can spend much less time in the designàcompileàerror-correct loop. Just-in-time validation helps users detect and correct programming errors earlier in the ETL development life cycle. Why do I have to redo the work I just did? In ETL development, schemas, transformation rules, connectivity objects, etc., can be reused in various situations. Using mouse-clicks to build and manage libraries of reusable design objects implies that the application development effort should decrease over time and as the library acquires more objects. I met a great company at SQL Pass that is trying to address many of these usability issues. Check them out at www.expressor-software.com. What other ease-of-use suggestions do you have for ETL software vendors? Please post your valuable comments. ?Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Best Practices, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: ETL

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  • SQL SERVER – Dedicated Access Control for SQL Server Express Edition – An error occurred while obtaining the dedicated administrator connection (DAC) port.

    - by pinaldave
    Recently I had faced very interesting situation. Due to some reason we were not able to login into the production server for one of client. The reason for the same was that server was very busy, we had to login into the system and bring server to normal situation. When all the attempts failed, I decided to login using Dedicated Administrator Connection (DAC). However when I attempted to connect using DAC it threw following error for me. C:\Users\pinald>sqlcmd -A -d master -S .\SQLEXPRESS Sqlcmd: Error: Microsoft SQL Server Native Client 11.0 : SQL Server Network Interfaces: An error occurred while obtaining the dedicated administrator connection (DAC) port. Make sure that SQL Browser is running, or check the error log for t he port number [xFFFFFFFF]. .Sqlcmd: Error: Microsoft SQL Server Native Client 11.0 : Login timeout expired.Sqlcmd: Error: Microsoft SQL Server Native Client 11.0 : A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online. I was bit taken a back as I knew that my commands are correct to login and if DAC does not work, there should be some serious reason for it. When inquired further about the SQL Server version I learned that it was SQL Server Express version deployed. To conserve resources, SQL Server Express does not listen on the DAC port. There is an additional step to be done if SQL Server Express has to be used with DAC. Enable TRACEFLAG on SQL Server Express will enable the connection by DAC possible. Here is the quick methods how one can enable DAC on SQL Server Express. Go to Start >> All Program >>Microsoft SQL Server (your version) >> Configuration Tools >> SQL Server Configuration Manager. Click on SQL Server Services >> Select your SQL Server Express version >> Right Click Properties >> select Startup Parameters Once on the Startup Parameter add the Startup parameter which is TRACEFLAG -T7806. Click on OK and RESTART SQL Server Express edition. Now once again try to connect to SQL Server Express edition and it will work just fine. This is absolutely documented method on BOL and SQL Server Express needs to be restarted. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Error Messages, SQL Interview Questions and Answers, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology Tagged: SQL Server Express

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