Monday, August 16, 2004

Avoid using sp_rename ...

sp_rename is the system stored procedure used to rename user created objects like “Stored procedure“, “Trigger“, “Table“ etc., This SP works pretty fine as long as you don't use it to rename a “Stored proc“, “Trigger“ or a “View“.

Let me try and explain this with an example. Normally once a SP, Trigger or a View is created an entry is made into sysobjects as well as syscomments tables.

For better understanding follow the following steps (examples uses Pubs database).

Step 1:

/*
Description: Sample procedure to demonstrate sp_rename issue
Author: M. Vadivel
Date: August 12, 2004
*/

Create Procedure FetchAuthorsDetails
As
Select * from Authors

Step 2: [self explanatory]

/*
Description: Query to see the stored proc details in sysobjects
Author: M. Vadivel
Date: August 12, 2004
*/

Select [name] from sysobjects where name like 'FetchAuthors%'

Step 3: [self explanatory]

/*
Description: Query to see the stored proc details in syscomments
Author: M. Vadivel
Date: August 12, 2004
*/

Select [text] from syscomments where [text] like '%FetchAuthors%'

Step 4:

Now let us try to rename this stored proc using sp_rename.

/*
Description: Query to rename the stored procedure into a new name
Author: M. Vadivel
Date: August 12, 2004
*/

sp_rename 'FetchAuthorsDetails','FetchAuthorsDetailsRenamed'

After this if you execute the queries mentioned in Step 2 and 3 you could find that in syscomments table still the old name is retained!!

In order to double check it, go to SQL Enterprise Manager and navigate to the Pubs database. If you check the SP name it would be the new name only. But just double click that SP and see the code within it. It would be refering to the old sp name i.e., 'FetchAuthorsDetails'.

So in order to avoid this confusion its always better to generate the script of the SP, trigger or view which you would like to rename. Then delete it and recreate it with a new name (using the script generated).