PL/SQL学习笔记之条件控制语句

一：IF-THEN语句

IF (condition) THEN
   commands;
END IF;

二：IF-THEN_ELSE语句

IF (condition) THEN
   S1;
ELSE
   S2;
END IF;

三：IF-THEN—ELSEIF—ELSE

IF(boolean_expression 1)THEN
   S1;
ELSIF( boolean_expression 2) THEN
   S2;
ELSIF( boolean_expression 3) THEN
   S3;
ELSE
   S4;
END IF;

四：CASE语句

CASE selector
    WHEN 'value1' THEN S1;
    WHEN 'value2' THEN S2;
    WHEN 'value3' THEN S3;
    ...
    ELSE Sn;  -- default case
END CASE;

CASE
    WHEN selector = 'value1' THEN S1;
    WHEN selector = 'value2' THEN S2;
    WHEN selector = 'value3' THEN S3;
    ...
    ELSE Sn;  -- default case
END CASE;