Re: Subselect with no records results in final empty set - Mailing list pgsql-general

From John R Pierce
Subject Re: Subselect with no records results in final empty set
Date
Msg-id 54CA9D89.2040502@hogranch.com
Whole thread Raw
In response to Re: Subselect with no records results in final empty set  ("Sterpu Victor" <victor@caido.ro>)
Responses Re: Subselect with no records results in final empty set
List pgsql-general
On 1/29/2015 12:36 PM, Sterpu Victor wrote:
>
> ON(null) never matched.

NULL is neither true nor false.

ON somefieldinthejoin IS NULL    would be a valid syntax.   except,
that's NOT a join condition, a join condition would be ON
left_table.something = right_table.something

> ON (1=1)

equivalent to ON TRUE

but that will cross join everything,  so if the left table has N rows
and the right table has M rows, you'll end up with N*M rows in the
result.  is that really what you want ??




--
john r pierce                                      37N 122W
somewhere on the middle of the left coast



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