On Thursday 31 Oct 2002 6:21 pm, Wei Weng wrote: > data | data1 | data2 > ------+-------+------- > 1 | foo | bar > 2 | greg | bar > 3 | pooh | bar > 4 | dah | peng > > I need a query that returns me the "data1" that satisfies the logic of > the following pseudo code: > > 1: select data2 into @out from test where data1 = 'pooh' > 2: select data1 from test where data2 = @out and data = 3
The most literal would be something like: SELECT t1.data1 FROM test t1 WHERE t1.data=3 AND t1.data2 IN (SELECT t2.data2 FROM test t2 WHERE t2.data1='pooh') You can probably get away without the t1/t2 stuff but that should make things clear. Since Postgresql isn't very good at optimising IN, you might want to rewrite it as an EXISTS query instead - see the manuals and mailing list archives for details. HTH -- Richard Huxton ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html