mysql 怎么写循环语句

DELIMITER $$

CREATE PROCEDURE example_while()
BEGIN
    DECLARE counter INT DEFAULT 0;
    WHILE counter < 5 DO
        SELECT counter;
        SET counter = counter + 1;
    END WHILE;
END$$

DELIMITER ;

CALL example_while();

DELIMITER $$

CREATE PROCEDURE example_repeat()
BEGIN
    DECLARE counter INT DEFAULT 0;
    REPEAT
        SELECT counter;
        SET counter = counter + 1;
    UNTIL counter >= 5 END REPEAT;
END$$

DELIMITER ;

CALL example_repeat();

DELIMITER $$

CREATE PROCEDURE example_loop()
BEGIN
    DECLARE counter INT DEFAULT 0;
    loop_label: LOOP
        SELECT counter;
        SET counter = counter + 1;
        IF counter >= 5 THEN
            LEAVE loop_label;
        END IF;
    END LOOP;
END$$

DELIMITER ;

CALL example_loop();

DELIMITER $$

CREATE PROCEDURE example_for()
BEGIN
    DECLARE counter INT DEFAULT 0;
    FOR counter IN 0..4 DO
        SELECT counter;
    END FOR;
END$$

DELIMITER ;

CALL example_for();