Re: IFNULL -> COALESCE

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Lee Kindness <lkindness(at)csl(dot)co(dot)uk>
Cc: Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: IFNULL -> COALESCE
Date: 2002-02-08 18:23:03
Message-ID: 24776.1013192583@sss.pgh.pa.us
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Lee Kindness <lkindness(at)csl(dot)co(dot)uk> writes:
> Okay, lets try that again...
> SELECT IFNULL(MAX(id), 0) + 1 from test;
> can be replaced by the following PostgreSQL query:
> SELECT COALESCE(MAX(id), 0) + 1 from test;

For any specific datatype that you might need this for, you could
provide a user-defined IFNULL function to avoid having to translate
your code. Might get a bit tedious if you are doing it for a lot
of different datatypes, however.

Not sure if it's worth adding a keyword and a grammar production
to get Postgres to do this for you. If it were part of a full-court
press to improve our Oracle compatibility, I wouldn't object, but
I'm not sure I see the point of doing just the one nonstandard
feature.

regards, tom lane

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