Tino Wildenhain <tino@wildenhain.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