select * from a;a|b-+-----1|primo2|(2 rows) SELECT CASE WHEN b IS NOT NULL
THEN 'pref.'||b||'.suf'
ELSE 'pref.'||'NULL'||'.suf'
END FROM a;
case
--------------
pref.primo.suf
pref.NULL.suf
(2 rows)
Jose'
Sascha Ziemann wrote:
"Gene Selkov Jr." <selkovjr@selkovjr.xnet.com>: | > the user manual describes the function IFNULL on page 38, but when I
| > try to use it I get the following error:
| >
| > users=> select ifnull (NULL, 'nix');
| > ERROR: No such function 'ifnull' with the specified attributes
|
| The manual seems to be obsolete. The related functions are named
| nullvalue and nonnullvalue, but neither takes more than one argument.
IFNULL isn't syntactic suguar. It is like C's "1 ? 1 : 0".
| > Or does anybody know a simple way to concatenate strings, which can be
| > NULL?
|
| Don't know the answer to this, but it appears to be wrong not to
| ignore NULLs in concatenation.
That is the way Postgresql works:
users=> select 'tach' || NULL;
ERROR: parser: parse error at or near ";"
users=> create function cat (text,text) returns text as 'begin return $1 || $2; end;' language 'plpgsql';
CREATE
users=> select cat ('tach', NULL);
ERROR: typeidTypeRelid: Invalid type - oid = 0
| Why not trust this job to your client-side
| code?
Because I do not write that code and because my computer isn't
religious enough to trust anybody ;-)
Sascha
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