Using a cursor with dynamic SQL in a stored procedure

Question

I have a dynamic SQL statement I\'ve created in a stored procedure. I need to iterate over the results using a cursor. I\'m having a hard time figuring out the right syntax.

Answer 1

First off, avoid using a cursor if at all possible. Here are some resources for rooting it out when it seems you can't do without:

There Must Be 15 Ways To Lose Your Cursors... part 1, Introduction

Row-By-Row Processing Without Cursor

That said, though, you may be stuck with one after all--I don't know enough from your question to be sure that either of those apply. If that's the case, you've got a different problem--the select statement for your cursor must be an actual SELECT statement, not an EXECUTE statement. You're stuck.

But see the answer from cmsjr (which came in while I was writing) about using a temp table. I'd avoid global cursors even more than "plain" ones....

Answer 2

Working with a non-relational database (IDMS anyone?) over an ODBC connection qualifies as one of those times where cursors and dynamic SQL seems the only route.

select * from a where a=1 and b in (1,2)

takes 45 minutes to respond while re-written to use keysets without the in clause will run in under 1 second:

select * from a where (a=1 and b=1)
union all
select * from a where (a=1 and b=2)

If the in statement for column B contains 1145 rows, using a cursor to create indidivudal statements and execute them as dynamic SQL is far faster than using the in clause. Silly hey?

And yes, there's no time in a relational database that cursor's should be used. I just can't believe I've come across an instance where a cursor loop is several magnitudes quicker.