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skywalker 47fc3374d0 documentation for new sql clauses case, coalesce and nullif contributed by Arno Brinkman <firebird@abvisie.nl>		2002-08-08 23:33:23 +00:00
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README.case	documentation for new sql clauses case, coalesce and nullif	2002-08-08 23:33:23 +00:00
README.coalesce	documentation for new sql clauses case, coalesce and nullif	2002-08-08 23:33:23 +00:00
README.nullif	documentation for new sql clauses case, coalesce and nullif	2002-08-08 23:33:23 +00:00

README.nullif

Function:
    Speicify an alternative value for a column to return when it has a NULL 
    value.

Author:
    Arno Brinkman <firebird@abvisie.nl>

Format:

  <case abbreviation> ::=
      NULLIF <left paren> <value expression> <comma> <value expression> <right paren>


Syntax Rules:
    1) NULLIF (V1, V2) is equivalent to the following <case specification>:
         CASE WHEN V1 = V2 THEN NULL ELSE V1 END


Examples:
A)
  UPDATE PRODUCTS
    SET STOCK = NULLIF(STOCK,0)