Question

I have dynamic SQL stored in a SQL table that I have to execute under certain conditions. Currently, we use cursors to handle that for us, but I was always told to avoid cursors when possible as they aren’t the most efficient way of doing things. So, my question is: how do I execute dynamic SQL without them (if there’s a way)? The entire system is built around this dynamic SQL mess, so there is no changing it.

For this, just assume the table has Id AS IDENTITY and SQL AS VARCHAR fields, where the SQL field contains the SQL to be executed (obviously).

EDIT:
Basically, I want to loop through the table and execute the SQL in the SQL column.

So, a row in the table will basically look like this:

ID   SQL
--   ----------------------
1    SELECT * FROM RECORD
2    SELECT * FROM PERSON
3    SELECT * FROM LOCATION

I haven’t written any code because what I’d write is a cursor to traverse through the table and execute it. I just don’t know of any other ways of looping a table and executing that string as a SQL query other than something like:

DECLARE @sql VARCHAR(MAX)

DECLARE _cursor CURSOR
FOR
    SELECT  [SQL]
    FROM    #tmp2

OPEN _cursor

FETCH NEXT FROM _cursor INTO @sql

WHILE @@FETCH_STATUS = 0 
    BEGIN
        PRINT ( @sql )
    END
CLOSE _cursor   
DEALLOCATE _cursor

Answer 1

You can use any number of concatenation tricks to make one big batch without using a cursor, I personally use the FOR XML trick a lot.

Here’s an overview:

http://www.simple-talk.com/sql/t-sql-programming/concatenating-row-values-in-transact-sql/

However, the cursor (while generally a code smell) isn’t going to contribute a terrible amount to the non-performance of this. And you will have an opportunity to handle errors etc a lot easier than with a single batch.

In addition, if you have DDL in some of those statements which has to be the first statement in a batch, then you would need to submit them in separate batches. EXEC or sp_executesql doesn’t implement any batch splitting like SSMS has the GO batch separator.