Thank you very much. Fine! Just two little questiton s more:
1) Can COALESCE take more than two alternatives?
2) Does it treat a zero length string as NULL or NOT NULL?
Esa Pikkarainen
Oliver Elphick wrote (24 Jan 01,):
> "Esa Pikkarainen" wrote:
> >This is maybe a novice question, but after all...
> >Say, I have a discussion forum application. There is an expiration
> >value for a whole board; then there are individual values for every
> >conference. If this individual value is NULL then the general value
> >should be used. How can I test this situation in a query (to
> >Postgresql):
> >I mean something like:
> >
> > Select (IF conf.expire NOTNULL conf.expire ELSE gen_expire)
> > as expire, ...
> >
> >Where is this in manuals if it is?
>
> SELECT COALESCE(expire, gen_expire) AS expire FROM conf;
>
> COALESCE takes the first non-null value from its list of parameters, like
> this:
>
> junk=# select * from junk where name is null;
> id | name
> ----+------
> 3 |
> (1 row)
>
> junk=# select id, coalesce(name,'no-name') from junk;
> id | case
> ----+---------
> 1 | Fred
> 2 | George
> 4 | sdf%df
> 3 | no-name
> (4 rows)
>
> --
> Oliver Elphick Oliver.Elphick@lfix.co.uk
> Isle of Wight http://www.lfix.co.uk/oliver
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> ========================================
> "If anyone has material possessions and sees his
> brother in need but has no pity on him, how can the
> love of God be in him?"
> I John 3:17
>
>
