Re: why isn't this subquery wrong?

"David G. Johnston" <david.g.johnston@xxxxxxxxx> · Thu, 20 Apr 2017 16:16:56 -0700

On Thu, Apr 20, 2017 at 3:17 PM, jonathan vanasco <postgres@xxxxxxxx> wrote:

SELECT foo_id
	FROM example_a__data
	WHERE foo_id IN (SELECT bar_id FROM example_a__rollup)
	;

Or write it the idiomatic way (i.e., as a proper semi-join):

SELECT foo_id
FROM example_a__data
WHERE EXISTS (SELECT 1 
                                 FROM example_a__rollup
                              WHERE example_a__rollup.bar_id = example_a__data.foo_id)

IME its harder to forget the table prefix when using this form.

David J.