mysql嵌套if演示

DELIMITER $$CREATE    /*mysql嵌套if演示*/    PROCEDURE `pfmalls`.`pfm_proc_test`    (a INT,   b INT    )   BEGIN   DECLARE c INT;   IF a IS NULL THEN   SET a = 0;ELSEIF a > 10 THENIF a < 15 THENSET a = 20;ELSEIF a > 10 THENSET a = 10;END IF;ELSE #严重注意 else后面不用跟then IF a > 30 THENSET a = 30;ELSESET a = 40;END IF;#set a = 30;END IF;   IF b IS NULL THEN   SET b = 0;   END IF;  SET c = a + b;   SELECT c AS SUM;       END$$DELIMITER ;/*执行: call(10,20);*/