|
Martin,
Thank you. SELECT statement returns lot of
columns.
I tried
select coalesce( (select 1,2 ), null);
but got
ERROR: subquery must return only one column
How to use your suggestion if select returns lot of columns
?
Andrus.
----- Original Message -----
Sent: Monday, June 21, 2010 10:14
PM
Subject: Re: How to force
select to return exactly one row
Try wrapping the entire statement in a COALESCE((statement),
<DEFAULT_VALUE>);
-m
2010/6/21 Andrus <kobruleht2@xxxxxx>
Autogenerated select statement contains 0 .. n left
joins:
SELECT somecolumns
FROM ko
LEFT JOIN t1 ON
t1.primarykey= ko.t1foreignkwey
...
LEFT JOIN tn ON tn.primarykey=
ko.tnforeignkwey
WHERE ko.primarykey='someprimarykeyvalue';
This
select can return only 0 or 1 rows depending if ko row with primary
key
'someprimarykeyvalue' exists or not.
Problem:
if there
is no searched primary key row in ko database, select should also
return
empty row.
To get this result I added right join:
SELECT
somecolumns
FROM ko
RIGHT JOIN (SELECT 1) _forceonerow ON true
LEFT
JOIN t1 ON t1.primarykey= ko.t1foreignkwey
...
LEFT JOIN tn ON
tn.primarykey= ko.tnforeignkwey
WHERE ko.primarykey is null or
ko.primarykey='someprimarykeyvalue';
but it still does not return row
if primary key row 'someprimarykeyvalue'
does not exist.
How to
force this statement to return one row always ?
Andrus.
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