How UPDATE and SELECT at the same time
I need to update some rows of开发者_如何学运维 the tables and then display these rows. Is there a way to do this with one single query and avoid this 2 query ? :
UPDATE table SET foo=1 WHERE boo=2
SELECT * from table WHERE ( foo=1 ) AND ( boo=2 )
In PostgreSQL v8.2 and newer you can do this using RETURNING
:
UPDATE table
SET foo=1
WHERE boo=2
RETURNING *
You can use a stored procedure in PL/pgSQL. Take a look at the [docs][1]
Something like this
CREATE FUNCTION run(fooVal int, booVal int)
RETURNS TABLE(fooVal int, booVal int)
AS $$
BEGIN
UPDATE table SET foo = fooVal WHERE boo= booVal;
RETURN QUERY SELECT fooVal, booVal from table WHERE ( foo = fooVal ) AND ( boo = booVal );
END;
$$ LANGUAGE plpgsql;
You will save the roundtrip time for sending another statement. This should not be a performance bottleneck. So short answer: Just use two queries. That's fine and this is how you do it in SQL.
[1]: http://www.postgresql.org/docs/8.4/static/plpgsql.html docs
You can use stored procedure or function. It will contains your queries.
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