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Re: sql join question

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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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