Hello, thanks Set, makes my test unnecessary!
But I'm thinking a little bit about my original problem. Would it make sense to add a tracker entry for optimization of subselects without reference to outer query? I think that they should get evaluated and transformed to something like a "or" connected list of simple compares. So delete from test where Id in ( select min(t.Id) FROM test t group by t.reference, t.key having count(*) > 1 ) could be transformed by the engine to delete from test where Id = 5 or Id = 6 or Id = 89 in case of select min(t.Id) FROM test t group by t.reference, t.key having count(*) > 1 would return 5,6,89 I've found several similar questions in my mail archive so I think I'm not the only one with such a problem. A common use case would be to remove duplicate entries for example to create a unique index. Any comments? -- Björn Reimer - RRZE
