CASE Statement
The CASE statement chooses from a sequence of conditions and runs a corresponding statement.
The simple CASE statement evaluates a single expression and compares it to several potential values.
The searched CASE statement evaluates multiple Boolean expressions and chooses the first one whose value is TRUE.
Description of the illustration simple_case_statement.gif
Description of the illustration searched_case_statement.gif
See:
Expression whose value is evaluated once and used to select one of several alternatives. selector can have any PL/SQL data type except BLOB, BFILE, or a user-defined type.
WHEN selector_value THEN statement
selector_value can be an expression of any PL/SQL type except BLOB, BFILE, or a user-defined type.
The selector_values are evaluated sequentially. If the value of a selector_value equals the value of selector, then the statement associated with that selector_value runs, and the CASE statement ends. Subsequent selector_values are not evaluated.
Caution:
Astatement can modify the database and invoke nondeterministic functions. There is no fall-through mechanism, as there is in the C switch statement.ELSE statement [statement ]...
The statements run if and only if no selector_value has the same value as selector.
Without the ELSE clause, if no selector_value has the same value as selector, the system raises the predefined exception CASE_NOT_FOUND.
A label that identifies the statement (see "statement ::=" and "label").
WHEN boolean_expression THEN statement
The boolean_expressions are evaluated sequentially. If the value of a boolean_expression is TRUE, the statement associated with that boolean_expression runs, and the CASE statement ends. Subsequent boolean_expressions are not evaluated.
Caution:
Astatement can modify the database and invoke nondeterministic functions. There is no fall-through mechanism, as there is in the C switch statement.ELSE statement [statement ]...
The statements run if and only if no boolean_expression has the value TRUE.
Without the ELSE clause, if no boolean_expression has the value TRUE, the system raises the predefined exception CASE_NOT_FOUND.
A label that identifies the statement (see "statement ::=" and "label").
See Also:
-
Oracle Database SQL Language Reference for information about the
NULLIFfunction -
Oracle Database SQL Language Reference for information about the
COALESCEfunction