Re: IN vs EXIIST
От | Darren Ferguson |
---|---|
Тема | Re: IN vs EXIIST |
Дата | |
Msg-id | Pine.LNX.4.44.0209191352010.8082-100000@thread.crystalballinc.com обсуждение исходный текст |
Ответ на | Re: IN vs EXIIST (Jean-Luc Lachance <jllachan@nsd.ca>) |
Список | pgsql-general |
I realized after he sent his notice this morning. On Thu, 19 Sep 2002, Jean-Luc Lachance wrote: > This is not what he wants. > > He wants all keys that have only true for x. > > > > Why areyou using the sub select. If you just want all the key1 where x is > > true then the following will work > > > > SELECT DISTINCT(key1) FROM a WHERE x = TRUE; > > > > If you want all rows and don't care about duplicates then remove the > > distinct. > > > > Hope this helps > > > > > > > > I've seen many posts saying that using IN is not optimal and replacing > > > it with EXISTS is much better. I've read the only docs but I can't > > > understand the difference between the two or how to convert. > > > > > > Can someone point me to some other docs or explain to me how to convert? > > > Or is my table schema wrong? > > > > > > Thanks! > > > > > > Jc > > > > -- Darren Ferguson
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