Hello! (Ruslan, this msg follows the one i just sent you) Why SELECT T1.IdOne, T2.IdTwo, T2.IdThree FROM T1, T2 WHERE T1.IdOne = T2.IdOne will give me duplicates if T1.Idone is defined not_nullable/indexed and disctinct one if T1.IdOne is defined not_nullable/indexed/UNIQUE ? Is it my light SQL knowledge or is there a 'problem' ? WilG