|The PostgreSQL 9.0 Reference Manual - Volume 1A - SQL Language Reference
by The PostgreSQL Global Development Group
Paperback (6"x9"), 454 pages
RRP £14.95 ($19.95)
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7.21.2 NOT IN
expression NOT IN (value [, ...])
The right-hand side is a parenthesized list of scalar expressions. The result is “true” if the left-hand expression's result is unequal to all of the right-hand expressions. This is a shorthand notation for
expression <> value1 AND expression <> value2 AND ...
Note that if the left-hand expression yields null, or if there are
no equal right-hand values and at least one right-hand expression yields
null, the result of the
NOT IN construct will be null, not true
as one might naively expect.
This is in accordance with SQL's normal rules for Boolean combinations
of null values.
x NOT IN yis equivalent to
NOT (x IN y)in all cases. However, null values are much more likely to trip up the novice when working with
NOT INthan when working with
IN. It is best to express your condition positively if possible.
|ISBN 9781906966041||The PostgreSQL 9.0 Reference Manual - Volume 1A - SQL Language Reference||See the print edition|