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.
On Thu, Mar 29, 2012 at 3:56 PM, David Salisbury <salisbury(at)globe(dot)gov>wrote:
> On 3/29/12 4:26 PM, Chris Angelico wrote:
>> On Fri, Mar 30, 2012 at 9:16 AM, David Salisbury<salisbury(at)globe(dot)gov>
>>> 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.
> Thanks guys! In fact I did see the difference between no row and a null
> 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.
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