Question

I have a SQL script that populates a temp column and then drops the column at the end of the script. The first time it runs, it works fine because the column exists, then it gets dropped. The script breaks the 2nd time because the column no longer exists, even though the IF statement ensures that it won’t run again. How do I get around SQL checking for this field?

IF EXISTS (SELECT name FROM syscolumns 
             WHERE name = 'COLUMN_THAT_NO_LONGER_EXISTS')
BEGIN
   INSERT INTO TABLE1
   (
     COLUMN_THAT_NO_LONGER_EXISTS,
     COLUMN_B,
     COLUMN_C
   )
   SELECT 1,2,3 FROM TABLE2

   ALTER TABLE TABLE1 DROP COLUMN COLUMN_THAT_NO_LONGER_EXISTS
END

Answer 1

I had a similar problem once and got round it by building all the queries as strings and executing them using the Exec() call. That way the queries (selects, inserts or whatever) don’t get parsed till they are executed.

It wasn’t pretty or elegant though.

e.g

exec('INSERT INTO TABLE1(COLUMN_THAT_NO_LONGER_EXISTS,COLUMN_B,COLUMN_C) SELECT 1,2,3 FROM TABLE2')