CASE SELECT syntax

On Thu, Jan 15, 2004 at 18:23:47 +0100,
Marco Lazzeri <marcomail@noze.it> wrote:

What about a SELECT syntax like that?

SELECT
CASE WHEN bar.foo_id IS NULL THEN bar.*
ELSE foo.*
FROM foo, bar

Anyway, I need a SELECT query that gets data from a FIRST TABLE if a
specific value in a SECOND TABLE is NULL or from SECOND TABLE itself if
the value IS NOT NULL.

Any suggestion?

You almost certainly want some join condition between foo and bar.
You can't actually use *. You will need a CASE for each column.
CASE statements need and END.

On Thu, 15 Jan 2004, Bruno Wolff III wrote:

On Thu, Jan 15, 2004 at 18:23:47 +0100,
Marco Lazzeri <marcomail@noze.it> wrote:

What about a SELECT syntax like that?

SELECT
CASE WHEN bar.foo_id IS NULL THEN bar.*
ELSE foo.*
FROM foo, bar

Anyway, I need a SELECT query that gets data from a FIRST TABLE if a
specific value in a SECOND TABLE is NULL or from SECOND TABLE itself if
the value IS NOT NULL.

Any suggestion?

You almost certainly want some join condition between foo and bar.
You can't actually use *. You will need a CASE for each column.
CASE statements need and END.

Alternatively (though it fails to use the 'CASE' syntax) would be to use
COALESCE. Something like:

SELECT COALESCE((SELECT foo_id FROM table2 WHERE ...),
(SELECT bar_id FROM table1 WHERE ...));

HTH
-frank