A problem I have encountered today seems to be a kind of “magic”: A Single INSERT statement that was checked for uniqueness was inserting duplicate rows into the table for each insert. All other parties in the system (Client, Server, etc.) sent the data only once and could not be the problem. Investigating the SQL Statement behind this insert shows this query (data and structure were changed): INSERT INTO TableX (A, B, C) SELECT ‘X’ AS A, 2 AS B,’2008-11-19 ‘AS C FROM DUMMY WHERE NOT EXISTS (SELECT...