Re: default value returned from sql stmt
| От | Ken Tanzer |
|---|---|
| Тема | Re: default value returned from sql stmt |
| Дата | |
| Msg-id | CAD3a31Xjvgc2T3EcoQoT=iPNJtZ0LxpAUdUFV26UHqOK-vp9ZQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: default value returned from sql stmt (David Salisbury <salisbury@globe.gov>) |
| Список | pgsql-general |
It depends on what exactly it is you're trying to do, and where your default is supposed to be used. Are you wanting a single number returned? in that case something like this
SELECT COALESCE((SELECT anum FROM t1 WHERE anum=4 [ LIMIT 1 ]),100)
that would get you back a 4 or 100 in this case. If your anums are not unique, you'd want the "LIMIT 1" included.
Ken
On Thu, Mar 29, 2012 at 3:56 PM, David Salisbury <salisbury@globe.gov> wrote:
Thanks guys! In fact I did see the difference between no row and a null
On 3/29/12 4:26 PM, Chris Angelico wrote:On Fri, Mar 30, 2012 at 9:16 AM, David Salisbury<salisbury@globe.gov> wrote:development=# select coalesce(anum,100) from t1 where anum = 4;
What you have there is rather different from COALESCE, as you're
looking for a case where the row completely doesn't exist. But you can
fudge it with an outer join.
Untested code:
WITH rowid AS (select 4 as anum) SELECT coalesce(anum,100) FROM rowid
LEFT JOIN t1 ON rowid.anum=t1.anum
However, you may simply want a WHERE [NOT] EXISTS predicate. There may
be other ways of achieving your goal, too.
value within a row. But it seemed there must be a way that I was missing.
It does look though that plpg is the way to go, otherwise it just seems
to obfuscate the code, or have other possible consequences.
-ds
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