Re: Can I create a function that returns many records?

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От Tom Lane
Тема Re: Can I create a function that returns many records?
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Msg-id 22054.964030918@sss.pgh.pa.us
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Ответ на Can I create a function that returns many records?  ("Joel Burton" <jburton@scw.org>)
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"Joel Burton" <jburton@scw.org> writes:
> Working through the documentation, I see examples using CREATE 
> FUNCTION METAPHONE(text) RETURNS setof tblPerson AS 'SELECT 
> * FROM tblPerson' LANGUAGE 'sql',  but this returns only a single 
> numeric value (that doesn't seem to correspond to anything.)

IIRC, you can build a function that returns a SETOF any simple datatype,
but the support for returning tuples is suffering from bit-rot.
(I imagine it worked, more or less, back in Berkeley days.)  If you can
live with returning one column at a time, you might be OK.

SELECT function-returning-set is a pretty peculiar notation anyway,
since SQL doesn't really have any concept of set data types in
expressions.  What's more likely to be supported someday is a
function-returning-set used as a source table in a SELECT's
from-clause, ie,
SELECT blah blah blah FROM function-returning-set(arguments) ...

This doesn't require any creative interpretation of SQL semantics
to figure out what to do with the multiple result rows.

BTW, is there a good reason why you don't just use a VIEW?
        regards, tom lane


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