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CASE
CASE
Syntax
80
• The argument to the function must be of type SMALLINT, INTEGER, NUMERIC, REAL, or
FLOAT.
• The result is of type NUMERIC.
Specifies a series of search conditions and associated result expressions. The general form is
called a searched case expression. SQL returns the value specified by the first result expression
whose associated search condition evaluates as true. If none of the search conditions evaluates
as true, the CASE expression returns a NULL value, or the value of some other default expression
if the CASE expression includes the ELSE clause.
CASE also supports syntax for a shorthand notation, called a simple case expression, for
evaluating whether one expression is equal to a series of other expressions.
searched_case_expr | simple_case_expr
searched_case_expr
simple_case_expr
CASE
Syntax
CASE
WHEN search_condition THEN { result_expr | NULL }
[ ... ]
[ ELSE expr | NULL ]
END
Syntax
CASE primary_expr
WHEN expr THEN { result_expr | NULL }
[ ... ]
[ ELSE expr | NULL ]
Specifies a searched case expression. It must be followed by one or more WHEN-THEN
clauses, each specifying a search condition and corresponding expression.
WHEN search_condition THEN { result_expr | NULL }
Specifies a search condition and corresponding expression. SQL evaluates
search_condition. If search_condition evaluates as true, CASE returns the value
specified by result_expr, or NULL, if the clause specifies THEN NULL.
If search_condition evaluates as false, SQL evaluates the next WHEN-THEN clause, if any,
or the ELSE clause, if it is specified.