On 11/22/06, Pringle, Ron <RPringle at aurora-il.org> wrote: > To close this out, turns out you don't need to use DISTINCT in the > query. The default behavior of UNION in MySQL is to remove duplicate > rows anyhow. So the final query now looks like: To clarify, you are saying that for a unioned set A and B, where A and/or B have duplicates within its own set, the union operation will remove such duplicates? So, it must combine sets and then perform the un-dupe over the entire set, rather than take set A and only append from set B if the item in set B is not found in A. Did you do any tests to make sure the DB does not use a different algorithm when it knows the two sets have no dupes already? -- Matt Warden Cleveland, OH, USA http://mattwarden.com This email proudly and graciously contributes to entropy.