Can UNION ALL be faster than JOINs or do my JOINs just suck?

Question

I have a Notes table with a uniqueidentifier column that I use as a FK for a variety of other tables in the database (don\'t worry, the uniqu

Answer 1

I may be wrong, but I think that you will get a better performance if you rewrite you JOIN version to

SELECT N.*  
FROM Notes N  
LEFT JOIN Leads L ON N.TargetUniqueID = L.UniqueID AND L.LeadID = @LeadID  
LEFT JOIN Quotes Q ON N.TargetUniqueID = Q.UniqueID  AND Q.LeadID = @LeadID
WHERE Q.LeadID IS NOT NULL OR L.LeadID IS NOT NULL