为什么mysql不允许获取游标中的用户定义变量？

我有这样的代码，mysql发布了一个错误：

行：

fetchcur\u recycle\u batch进入@id、@created\u by、@created\u date发布错误

有人知道为什么mysql不允许获取用户定义的变量吗

CREATE DEFINER=`root`@`localhost` PROCEDURE `generate_row`()
BEGIN

    DECLARE done TINYINT DEFAULT FALSE;
    DECLARE cur_recycle_batch CURSOR FOR SELECT 
                                                id, created_by, created_date
                                            FROM
                                                outsourcing_recycle_batch
                                            order by created_date;

    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    START transaction;

        OPEN cur_recycle_batch;

            insert_loop : loop

                FETCH cur_recycle_batch INTO @id, @created_by, @created_date;

                IF done THEN

                    LEAVE insert_loop;
                END IF;

                INSERT INTO `test_db`.`outsourcing_recycle_batch_history_list`
                (`outsourcing_recycle_batch_pk`,
                `outsourcing_history_pk`,
                `created_by`,
                `created_by_full_name`,
                `created_date`)
                VALUES
                (@id,
                1,
                @created_by,
                'AAAAAAAA',
                @created_date);


            END LOOP;

        CLOSE cur_recycle_batch;

    commit;

END

有一个解决方法：
声明
局部变量，而不是依赖用户变量

CREATE DEFINER=`root`@`localhost` PROCEDURE `generate_row`()
BEGIN
    DECLARE local_id INT;
    DECLARE local_created_by VARCHAR(20);
    DECLARE local_created_date DATE;
    DECLARE done TINYINT DEFAULT FALSE;
    DECLARE cur_recycle_batch CURSOR FOR SELECT id, created_by, created_date
                                            FROM outsourcing_recycle_batch
                                            ORDER BY created_date;

    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
    START transaction;
        OPEN cur_recycle_batch;
            insert_loop : loop
                FETCH cur_recycle_batch INTO local_id, local_created_by, local_created_date;
                IF done THEN
                    LEAVE insert_loop;
                END IF;
                INSERT INTO `test_db`.`outsourcing_recycle_batch_history_list`
                (`outsourcing_recycle_batch_pk`,
                `outsourcing_history_pk`,
                `created_by`,
                `created_by_full_name`,
                `created_date`)
                VALUES
                (local_id,
                1,
                local_created_by,
                'AAAAAAAA',
                local_created_date);
            END LOOP;
        CLOSE cur_recycle_batch;
    commit;
END

考虑到这种解决方法，将FETCH实现到用户变量中肯定从来没有优先权

CREATE DEFINER=`root`@`localhost` PROCEDURE `generate_row`()
BEGIN
    DECLARE local_id INT;
    DECLARE local_created_by VARCHAR(20);
    DECLARE local_created_date DATE;
    DECLARE done TINYINT DEFAULT FALSE;
    DECLARE cur_recycle_batch CURSOR FOR SELECT id, created_by, created_date
                                            FROM outsourcing_recycle_batch
                                            ORDER BY created_date;

    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
    START transaction;
        OPEN cur_recycle_batch;
            insert_loop : loop
                FETCH cur_recycle_batch INTO local_id, local_created_by, local_created_date;
                IF done THEN
                    LEAVE insert_loop;
                END IF;
                INSERT INTO `test_db`.`outsourcing_recycle_batch_history_list`
                (`outsourcing_recycle_batch_pk`,
                `outsourcing_history_pk`,
                `created_by`,
                `created_by_full_name`,
                `created_date`)
                VALUES
                (local_id,
                1,
                local_created_by,
                'AAAAAAAA',
                local_created_date);
            END LOOP;
        CLOSE cur_recycle_batch;
    commit;
END

举个例子，还有一个更简单的解决方法：根本不使用光标，只使用插入一组行

CREATE DEFINER=`root`@`localhost` PROCEDURE `generate_row`()
BEGIN
    INSERT INTO `test_db`.`outsourcing_recycle_batch_history_list`
        (`outsourcing_recycle_batch_pk`,
        `outsourcing_history_pk`,
        `created_by`,
        `created_by_full_name`,
        `created_date`)
    SELECT id, 1, created_by, 'AAAAAAAA', created_date
    FROM outsourcing_recycle_batch;
END

我不知道你是否简化了你的例子。您可能需要使用光标对值进行其他逐行操作，而不是简单地插入。
基本上这似乎是一个设计问题。在这种情况下使用a有什么特殊原因吗？。还要检查函数：。我在问题中使用了声明变量。我最初使用用户定义变量是为了节省几行代码，但我很好奇为什么mysql不允许这样做。在这种情况下，最后一个插入ID是正确的。谢谢你的建议。