> > Try to get some records not in another table. As the following, please
> advise which one will be the best way to do. Or is there any other way to do > better? > > SELECT DISTINCT a.c1 > FROM test_j2 a > WHERE a.c1 NOT IN (SELECT DISTINCT b.c1 FROM test_j1 b); > > SELECT a.c1 FROM test_j2 a > EXCEPT > SELECT b.c1 FROM test_j1 b; > IN resp. NOT IN clauses are known to be slow. SELECT DISTINCT a.c1 FROM test_j2 a WHERE NOT EXISTS (SELECT b.c1 FROM test_j1 b WHERE b.c1 = a.c1) ; Can't tell if EXISTS performs better than EXCEPT, have a look at the EXPLAIN output. Regards, Christoph ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
