Saturday, February 25, 2012

A question on subquery return

Here is subquery for a table, called pStatus

pStatus
userid
status

select 1 from pStatus where userid='Robert' and status='p'

How to modify this query so that it also return true if there is't an entry for userid 'Robert'?

Thanks,

vHow about:

where (not exists (select 1 from pStatus where userid='Robert')
or exists (select 1 from pStatus where userid='Robert' and status='p'))|||Thanks Tony.

That is quick and sharp one.

v.|||When I posted this question, I was thinking about using only one "select". The subquery is a small section of a long query with near 1,700 characters. And there are 10 similar subqueries in the query statement needed to have the same change. After running the planner, the performane doesn't seem too bad.

Nested Loop (cost=1.16..33.58 rows=1 width=398) (actual time=2.00..2.00 rows=0 loops=1)

...
Total runtime: 7.00 msec

Only few data at this moment.

v.

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