Thursday, December 16, 2010

Dynamically Generating T-SQL Statements!

So you have many databases, objects, etc. and you want to massively administer it right?

In some of my previous posts I explained the undocumented stored procedures "sp_msforeachdb" and "sp_msforeachtable" that allow you to massively perform changes on all databases and tables within a SQL Server instance.

But isn't it handier to generate dynamic T-SQL for doing that? I believe it is!

By using some of the catalog views in SQL Server 2005 or later you can easily do that.

The idea is to use a basic SELECT statement and then dynamically build the T-SQL expression that eventually will generate the desired T-SQL code.

Here are some examples (before running the code, right-click in the query window, then select "Results To" and finally "Results to Text"):

Example 1: See the physical files used for each database

SELECT
'USE '+ name +';'+' SELECT name,physical_name FROM SYS.DATABASE_FILES' FROM SYS.databases

Example 2: Change the schema owner for all tables within a database

SELECT
'ALTER SCHEMA [NEW_SCHEMA_NAME] TRANSFER ' + s.Name + '.' + t.Name FROM sys.Tables t INNER JOIN
sys.Schemas s on t.schema_id = s.schema_id WHERE s.Name = ['OLD_SCHEMA_NAME']

Example 3: Change the schema owner for all stored procedures within a database
SELECT
'ALTER SCHEMA [NEW_SCHEMA_NAME] TRANSFER ' + s.Name + '.' + sp.Name FROM sys.Procedures sp INNER JOIN
sys.Schemas s on sp.schema_id = s.schema_id WHERE s.Name = ['OLD_SCHEMA_NAME']

Example 4: See all the views for each database
SELECT
'USE '+ s.name +';'+' SELECT * FROM sys.views' FROM SYS.databases s

Example 5: Change the compatibility level for all the databases to 100 (SQL Server 2008)
SELECT
'ALTER DATABASE '+ name + ' SET COMPATIBILITY_LEVEL = 100' FROM SYS.DATABASES

Example 6: Set all the databases to READ ONLY mode
SELECT
'ALTER DATABASE '+ name + ' SET READ_ONLY WITH ROLLBACK IMMEDIATE' FROM SYS.DATABASES

Example 7: Set all the databases to READ/WRITE mode
SELECT
'ALTER DATABASE '+ name + ' SET READ_WRITE WITH ROLLBACK IMMEDIATE' FROM SYS.DATABASES

... and the list goes on!

When using this technique along with the information retrieved from the catalog views, the possibilities are endless!

Yes, you still need to manually execute each generated T-SQL statement but the good thing is that the statements are being generated dynamically and by manually executing them, you have more control over your SQL Server instance.

I hope this helps!

Until next time!


P.S. The above sample code is intended only for demo purposes. Do not use it on Production systems. Whenever you massively modify database objects you need to be very careful with your data. Always backup your data!
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Artemakis Artemiou [MVP]

Author & Editor

Artemakis Artemiou is a Senior SQL Server Architect, Software Developer and Microsoft Data Platform MVP. He is also an author, regular blogger, president of Cyprus.NET User Group and CY Country leader of INETA-EU. He is also the creator of DBA Security Advisor and In-Memory OLTP Simulator. Artemakis is a frequent guest author of worldwide well-respected online journals where he writes articles focusing on many SQL Server topics.

Reference: The SQL Server and .NET Hub (http://www.sqlnethub.com)

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