Re: table column information
От | Steve Crawford |
---|---|
Тема | Re: table column information |
Дата | |
Msg-id | 200405171047.49867.scrawford@pinpointresearch.com обсуждение исходный текст |
Ответ на | Re: table column information ("Scot L. Harris" <webid@cfl.rr.com>) |
Список | pgsql-php |
On Sunday 16 May 2004 8:16 pm, Scot L. Harris wrote: > On Sun, 2004-05-16 at 22:55, Andrew McMillan wrote: > > On Mon, 2004-05-17 at 00:19 +0000, ljb wrote: > > > > But I don't think I want to select the entire contents of the > > > > table every time I want to get the names of the columns. I > > > > know this will work but I think performance will be very > > > > poor. > > > > > > You almost got it - just do "select * from tablename where > > > 0=1", which returns no rows but will give you the fieldnames. A > > > portable and (I think) efficient way to get table column names. > > > > It can be a cute trick, and I use it myself from time to time > > (especially for "CREATE TABLE AS SELECT ..." where I want an > > empty table with the same structure, pre v 7.4 which can do this > > anyway). You should be aware however that as written above it > > will almost invariably force a full-table scan! Depending on your needs you can also use: select * from tablename limit 0; Slow machine, 3.3 million row table: 4 milliseconds. No full table scan there. Cheers, Steve
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