Re: SQL Question
От | Brian |
---|---|
Тема | Re: SQL Question |
Дата | |
Msg-id | 3.0.5.32.20011112105422.0094d7b0@pop.we.mediaone.net обсуждение исходный текст |
Ответ на | Re: (John Burski <John.Burski@911ep.com>) |
Список | pgsql-novice |
This was correctly answered on another list by Steve Miskovitz. I am posting it here for those of you who have been working this. There is more in depth info about the sql technique heuses in his solution at the SQL Tutor: http://w3.one.net/~jhoffman/sqltut.htm#More_Subqueries It is essentially a NOT EXISTS in a (subquery) Here is the answer which I copied and pasted making the appropriate table name and field changes into my real world application,(though magic could be cool.) --------------------------- from: Steve Miskovitz <steve@collegepublisher.com> --------------------------- Subject: RE: SQL Question here is a straight forward way : SELECT TR.1_id FROM Trick TR WHERE NOT EXISTS ( SELECT * FROM Trick-Magician-Knows TMK WHERE TMK.1_id = TR.1_id AND TMK.2_id = ?) So it selects all tricks that DO NOT have a corresponding entry in the Trick-Magician-Knows table for a given magician. Switch the ? with 2_id of the magician.
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