45 | Conditional Statements in ORACLE PL/SQL | Oracle PL/SQL Programming
IF THEN ELSIF Statement
The IF THEN ELSIF statement has this structure:
IF condition_1 THEN
statements_1
ELSIF condition_2 THEN
statements_2
[ ELSIF condition_3 THEN
statements_3
]...
[ ELSE
else_statements
]
END IF;
The IF THEN ELSIF statement runs the first statements for which condition is true. Remaining conditions are not evaluated. If no condition is true, the else_statements run, if they exist; otherwise, the IF THEN ELSIF statement does nothing. (For complete syntax, see "IF Statement".)
In Example 4-4, when the value of sales is larger than 50000, both the first and second conditions are true. However, because the first condition is true, bonus is assigned the value 1500, and the second condition is never tested. After bonus is assigned the value 1500, control passes to the DBMS_OUTPUT.PUT_LINE invocation.
A single IF THEN ELSIF statement is easier to understand than a logically equivalent nested IF THEN ELSE statement:
-- IF THEN ELSIF statement
IF condition_1 THEN statements_1;
ELSIF condition_2 THEN statements_2;
ELSIF condition_3 THEN statement_3;
END IF;
-- Logically equivalent nested IF THEN ELSE statements
IF condition_1 THEN
statements_1;
ELSE
IF condition_2 THEN
statements_2;
ELSE
IF condition_3 THEN
statements_3;
END IF;
END IF;
END IF;
The simple CASE statement has this structure:
CASE selector
WHEN selector_value_1 THEN statements_1
WHEN selector_value_2 THEN statements_2
...
WHEN selector_value_n THEN statements_n
[ ELSE
else_statements ]
END CASE;]
The selector is an expression (typically a single variable). Each selector_value can be either a literal or an expression. (For complete syntax, see "CASE Statement".)
The simple CASE statement runs the first statements for which selector_value equals selector. Remaining conditions are not evaluated. If no selector_value equals selector, the CASE statement runs else_statements if they exist and raises the predefined exception CASE_NOT_FOUND otherwise.
Note:
As in a simple CASE expression, if the selector in a simple CASE statement has the value NULL, it cannot be matched by WHEN NULL (see Example 2-51). Instead, use a searched CASE statement with WHEN condition IS NULL (see Example 2-53).
45 | Conditional Statements in ORACLE PL/SQL | Oracle PL/SQL Programming
#if_else #if_elsif_else #conditional_statement #oracleplsql
