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.

Topics:

• Syntax

• Semantics

• Examples

• Related Topics

Syntax

simple_case_statement ::=

searched_case_statement ::=

See:

• boolean_expression ::=

• statement ::=

Semantics

simple_case_statement

selector

An expression whose value is evaluated once and used to select one of several alternatives. The value of selector can be of any PL/SQL type except BLOB, BFILE, or a user-defined type.

WHEN selector_value THEN statement

The selector_values are evaluated sequentially. If the value of a selector_value equals the value of selector, the statement associated with that selector_value runs, and the CASE statement ends. Subsequent selector_values are not evaluated.

A selector_value can be of any PL/SQL type except BLOB, BFILE, or a user-defined type.

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 a CASE_NOT_FOUND exception.

label

A label that identifies the statement (see the syntax diagram statement ::= and the description of label).

searched_case_statement

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.

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 a CASE_NOT_FOUND exception.

label

A label that identifies the statement (see the syntax diagram statement ::= and the description of label).

Examples

• Example 4-6, "Simple CASE Statement"

• Example 4-7, "Searched CASE Statement"

Related Topics

In this chapter:

• "IF Statement"

In other chapters:

• "CASE Expressions"

• "Conditional Selection Statements"

• "Simple CASE Statement"

• "Searched CASE Statement"