Re: Combining text fields

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От Nabil Sayegh
Тема Re: Combining text fields
Дата
Msg-id 3F913FBB.50203@e-trolley.de
обсуждение исходный текст
Ответ на Combining text fields  (Doug Silver <dsilver@urchin.com>)
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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
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