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PostgreSQL Reference Manual - Volume 1 - SQL Language Reference
by The PostgreSQL Global Development Group
Paperback (6"x9"), 716 pages
ISBN 0954612027
RRP £32.00 ($49.95)

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7.13.3 NULLIF

NULLIF(value1, value2)

The NULLIF function returns a null value if value1 and value2 are equal; otherwise it returns value1. This can be used to perform the inverse operation of the COALESCE example given above:

SELECT NULLIF(value, '(none)') ...

If value1 is (none), return a null, otherwise return value1.

ISBN 0954612027PostgreSQL Reference Manual - Volume 1 - SQL Language ReferenceSee the print edition