Oracle PL/SQL – 嵌套的 IF-THEN-ELSE 语句
简述
在 PL/SQL 编程中嵌套 IF-ELSE 语句，这意味着您可以使用一个 IF 要么 ELSE IF 在另一个内部声明 IF 要么 ELSE IF 声明。
句法
IF( boolean_expression 1)THEN
-- executes when the boolean expression 1 is true
IF(boolean_expression 2) THEN
-- executes when the boolean expression 2 is true
sequence-of-statements;
END IF;
ELSE
-- executes when the boolean expression 1 is not true
else-statements;
END IF;
例子
DECLARE
a number(3) := 100;
b number(3) := 200;
BEGIN
-- check the boolean condition
IF( a = 100 ) THEN
-- if condition is true then check the following
IF( b = 200 ) THEN
-- if condition is true then print the following
dbms_output.put_line('Value of a is 100 and b is 200' );
END IF;
END IF;
dbms_output.put_line('Exact value of a is : ' || a );
dbms_output.put_line('Exact value of b is : ' || b );
END;
/
在 SQL 提示符下执行上述代码时，会产生以下结果 -
Value of a is 100 and b is 200
Exact value of a is : 100
Exact value of b is : 200
PL/SQL procedure successfully completed.