From: | Greg Stark <gsstark(at)mit(dot)edu> |
---|---|
To: | Josh Berkus <josh(at)agliodbs(dot)com> |
Cc: | Stefan Bill <sjb26(at)yahoo(dot)com>, pgsql-sql(at)postgresql(dot)org |
Subject: | Re: LEAST and GREATEST functions? |
Date: | 2003-07-01 16:29:16 |
Message-ID: | 87d6gu2otf.fsf@stark.dyndns.tv |
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Lists: | pgsql-sql |
Josh Berkus <josh(at)agliodbs(dot)com> writes:
> Stefan,
>
> > I know the LEAST and GREATEST functions are not part
> > of standard SQL, but they sure were handy where I came
> > from (Oracle-land).
>
> Um, what's wrong with MAX and MIN, exactly?
MAX and MIN are single-parameter aggregate functions. LEAST and GREATEST are
two-parameter (though in postgres they could be defined for 3 and more
parameters) scalar functions.
eg:
SELECT max(a) FROM bar
would return a single tuple with the maximum value of a from amongst every
record. whereas:
SELECT greatest(a,b) FROM bar
would return one tuple for every record in the table with a single value
representing the greater of bar.a and bar.b.
You could define your own functions to do this but it would be tiresome to
define one for every datatype.
--
greg
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