From: | Nabil Sayegh <postgresql(at)e-trolley(dot)de> |
---|---|
To: | Doug Silver <dsilver(at)urchin(dot)com> |
Cc: | pgsql-novice(at)postgresql(dot)org |
Subject: | Re: Combining text fields |
Date: | 2003-10-18 13:27:23 |
Message-ID: | 3F913FBB.50203@e-trolley.de |
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Thread: | |
Lists: | pgsql-novice |
Doug Silver wrote:
> I just want to confirm that this is the correct behavior for the return value
> when combining text fields together. If one of the fields is NULL, then the
> return value of field1+field2 also becomes NULL. If this is correct, is the
> proper way to get around this to use a default value of '' for such fields?
This is correct behaviour (every comparison with NULL returns NULL)
http://developer.postgresql.org/docs/postgres/functions-comparison.html
-------------------------------8<----------------------------------------
Some applications may (incorrectly) require that expression = NULL
returns true if expression evaluates to the null value. To support these
applications, the run-time option transform_null_equals can be turned on
(e.g., SET transform_null_equals TO ON;). PostgreSQL will then convert x
= NULL clauses to x IS NULL. This was the default behavior in releases
6.5 through 7.1.
-------------------------------8<----------------------------------------
HTH
--
e-Trolley Sayegh & John, Nabil Sayegh
Tel.: 0700 etrolley /// 0700 38765539
Fax.: +49 69 8299381-8
PGP : http://www.e-trolley.de
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