From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Tino Wildenhain <tino(at)wildenhain(dot)de> |
Cc: | "Nigel J(dot) Andrews" <nandrews(at)investsystems(dot)co(dot)uk>, Pgsql-General <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: concenation of strings and null values |
Date: | 2003-10-07 10:28:43 |
Message-ID: | 23091.1065522523@sss.pgh.pa.us |
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Lists: | pgsql-general |
Tino Wildenhain <tino(at)wildenhain(dot)de> writes:
> Can someone enlighten me if this is
> in accordance to some not so transparent
> rules of SQL92 or '99 and if so, how
> to work around this?
It is per spec: in SQL92 6.13 <string value expression>:
2) If <concatenation> is specified, then let S1 and S2 be the re-
sult of the <character value expression> and <character factor>,
respectively.
Case:
a) If either S1 or S2 is the null value, then the result of the
<concatenation> is the null value.
regards, tom lane
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