两个游标在mysql中不起作用

DECLARE done INT DEFAULT FALSE;
DECLARE col1 INT;
DECLARE col2 VARCHAR(255);
DECLARE cur CURSOR FOR SELECT column1, column2 FROM table_name;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

OPEN cur;

read_loop: LOOP
    FETCH cur INTO col1, col2;
    IF done THEN
        LEAVE read_loop;
    END IF;
    
    -- 执行操作
    -- ...
    
END LOOP;

CLOSE cur;

CREATE TEMPORARY TABLE temp_table
SELECT column1, column2 FROM table_name;

-- 执行操作
-- ...

DROP TEMPORARY TABLE temp_table;