How to use the result of a complicated query in self-join?

I'm writing a stored procedure on SQL Server 2000.

I've written a complicated select statement that takes 18 seconds to run.

The question is开发者_运维技巧, how can I self-join the result correctly and efficiently?

Is it possible to manage it in a single select statement without repeating the big query statement that I currently have? Or should I save the result in a table variable or temp table?

Many thanks.

If the original query runs a long time, but the result is small, yes, you could consider a temporary / helper table, and run your second query (the self-join) on that table.

This may also help keep your approach modular / maintainable. And you'll be able to tune performance on that long-running query without your second one staring you in the face in the meantime.