Mysql(10)_存储过程与流程控制

-- ----------------------------
-- Procedure structure for `proc_adder`
-- ----------------------------
DROP PROCEDURE IF EXISTS `proc_adder`;
DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `proc_adder`(IN a int, IN b int, OUT sum int)
BEGIN
    #Routine body goes here...

    DECLARE c int;
    if a is null then set a = 0; 
    end if;
  
    if b is null then set b = 0;
    end if;

    set sum  = a + b;
END
$$
DELIMITER ;

SET @b=5;                 -- 把5传给第二个参数b
CALL proc_adder(2,@b,@s); -- 调用存储过程
SELECT @s as sum;         

CALL proc_adder(3,3,@s);
SELECT @s as sum;

-- ----------------------------
-- Procedure structure for `proc_adder`
-- ----------------------------
DROP PROCEDURE IF EXISTS `proc_if`;
DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `proc_if`(IN type int)
BEGIN
    #Routine body goes here...

    DECLARE c VARCHAR(500);
    IF type =0 THEN 
          SET c= ‘param is 0‘;
    ELSEIF type = 1 THEN 
          SET c=‘param is 1‘;
    ELSE
          SET c=‘param is others,not 0 or 1‘;
    END IF;
    SELECT c;
END
$$
DELIMITER ;

SET @type =1;
CALL proc_if(@type)

-- ----------------------------
-- Procedure structure for `proc_adder`
-- ----------------------------
DROP PROCEDURE IF EXISTS `proc_case`;
DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `proc_case`(IN type int)
BEGIN
    #Routine body goes here...

    DECLARE c VARCHAR(500);
    CASE type 
    WHEN 0 THEN 
       SET c=‘param is 0‘;
    WHEN 1 THEN 
       SET c = ‘param is 1‘;
    ELSE
       SET c = ‘param is others,not 0 or 1‘;
    END CASE;
    SELECT c;
END
$$
DELIMITER ;

SET @type =1;
CALL proc_case(@type)

-- ----------------------------
-- Procedure structure for `proc_adder`
-- ----------------------------
DROP PROCEDURE IF EXISTS `proc_while`;
DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `proc_while`(IN n int)
BEGIN
    #Routine body goes here...

    DECLARE i INT ;
    DECLARE s INT ;
    SET i = 0;
    SET s = 0;
    WHILE i <= n DO
     SET s = s+i;
     SET i = i+1;
    END WHILE;
    SELECT s;
END $$
DELIMITER ;

SET @n =100;
CALL proc_while(@n);