Re: Setting a default value for a select statement without results - Mailing list pgsql-sql

2013/2/6 JORGE MALDONADO <jorgemal1960@gmail.com>:
> I have an UPDATE query with the following general structure:
>
> UPDATE table1 SET (SELECT field FROM table2 WHERE conditions ORDER BY
> order_field LIMIT 1)
>
> Is it possible to assign a default value in case no results are returned by
> the SELECT statement?

One option would be to do something with UNION along these lines:

UPDATE table1 SET field = (SELECT field FROM table2 WHERE conditions     UNION  SELECT 'default_value' WHERE NOT EXISTS
(SELECTfield FROM table2
 
WHERE conditions )  ORDER BY order_field LIMIT 1 )

HTH

Ian Barwick