mysql单表内循环

DELIMITER //

CREATE PROCEDURE process_data()
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE id INT;
    DECLARE value VARCHAR(255);
    DECLARE cur CURSOR FOR SELECT id, value FROM your_table;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO id, value;
        IF done THEN
            LEAVE read_loop;
        END IF;
        -- 在这里进行数据处理
        UPDATE your_table SET processed = TRUE WHERE id = id;
    END LOOP;

    CLOSE cur;
END //

DELIMITER ;

DELIMITER //

CREATE PROCEDURE process_data()
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE id INT;
    DECLARE value VARCHAR(255);
    DECLARE cur CURSOR FOR SELECT id, value FROM your_table;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
    DECLARE counter INT DEFAULT 0;
    DECLARE max_iterations INT DEFAULT 1000;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO id, value;
        IF done THEN
            LEAVE read_loop;
        END IF;
        -- 在这里进行数据处理
        UPDATE your_table SET processed = TRUE WHERE id = id;
        SET counter = counter + 1;
        IF counter >= max_iterations THEN
            LEAVE read_loop;
        END IF;
    END LOOP;

    CLOSE cur;
END //

DELIMITER ;