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  • mysql流控制语句(LOOP, REPEAT, WHILE)

    1.loop
    语法:
    [begin_label:] LOOP
        statement_list
    END LOOP [end_label]
    例子:
    CREATE PROCEDURE doiterate(p1 INT) BEGIN label1: LOOP SET p1 = p1 + 1; IF p1 < 10 THEN ITERATE label1;// ITERATE can appear only within LOOPREPEAT, and WHILE statements. ITERATE means start the loop again.” END IF; LEAVE label1;// LEAVE can be used within BEGIN ... END or loop constructs (LOOPREPEATWHILE). END LOOP label1; SET @x = p1; END;
    2.repeat
    语法
    [begin_label:] REPEAT
        statement_list
    UNTIL search_condition
    END REPEAT [end_label]

    例子:
    mysql> delimiter //
    
    mysql> CREATE PROCEDURE dorepeat(p1 INT)
        -> BEGIN
        ->   SET @x = 0;
        ->   REPEAT
        ->     SET @x = @x + 1;
        ->   UNTIL @x > p1 END REPEAT;
        -> END
        -> //
    Query OK, 0 rows affected (0.00 sec)
    
    mysql> CALL dorepeat(1000)//
    Query OK, 0 rows affected (0.00 sec)
    
    mysql> SELECT @x//
    +------+
    | @x   |
    +------+
    | 1001 |
    +------+
    1 row in set (0.00 sec)

    3.while
    语法
    [begin_label:] WHILE search_condition DO
        statement_list
    END WHILE [end_label]
    例子:
    CREATE PROCEDURE dowhile()
    BEGIN
      DECLARE v1 INT DEFAULT 5;
    
      WHILE v1 > 0 DO
        ...
        SET v1 = v1 - 1;
      END WHILE;
    END;

    4.label标记语法
    [begin_label:] BEGIN
        [statement_list]
    END [end_label]
    
    [begin_label:] LOOP
        statement_list
    END LOOP [end_label]
    
    [begin_label:] REPEAT
        statement_list
    UNTIL search_condition
    END REPEAT [end_label]
    
    [begin_label:] WHILE search_condition DO
        statement_list
    END WHILE [end_label]




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  • 原文地址:https://www.cnblogs.com/wyzs/p/6223230.html
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