Re: sql join question
От | Scott Frankel |
---|---|
Тема | Re: sql join question |
Дата | |
Msg-id | a435cfd8b41af5ab914176d17dae94c4@pacbell.net обсуждение исходный текст |
Ответ на | Re: sql join question (Ragnar Hafstað <gnari@simnet.is>) |
Список | pgsql-general |
Got it. Thanks! Scott On Mar 1, 2005, at 10:52 PM, Ragnar Hafstað wrote: > On Tue, 2005-03-01 at 16:51 -0800, Scott Frankel wrote: >> Sweet! And not so sweet. >> >> The natural join worked beautifully with my test schema; but it failed >> to yield any rows with my real-world schema. I think I've tracked >> down >> why: duplicate column names. i.e.: >> ... >> CREATE TABLE palettes (palette_pkey SERIAL PRIMARY KEY, >> palette_name text UNIQUE DEFAULT NULL, >> qwe text); >> >> CREATE TABLE tones (tone_pkey SERIAL PRIMARY KEY, >> tone_name text UNIQUE DEFAULT NULL, >> palette_pkey integer REFERENCES palettes, >> qwe text); >> >> Are the 'qwe' columns in both tables clobbering each other and >> preventing the >> join from succeeding? > > the docs really explain this better than I can, but a > table1 NATURAL JOIN table2 > is shorthand fo a > table1 JOIN table2 USING (list_of_common_keys) > > so: > select color_name from palettes > join tones USING (palette_pkey) > join colors USING (tone_pkey) > where palette_name='plt1'; > > see: > http://www.postgresql.org/docs/8.0/interactive/sql-select.html > > gnari > > >
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