mysql递归删除子节点

CREATE DEFINER=`root`@`%` PROCEDURE `DeleteChildren`(IN rootId INT)  
BEGIN  
    DECLARE done INT DEFAULT 0;  
    DECLARE childId INT;  
    -- 定义游标遍历所有子节点  
    DECLARE cur CURSOR FOR SELECT id FROM system_menu WHERE parent_id = rootId;  
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;  

    OPEN cur;  
    read_loop: LOOP  
        FETCH cur INTO childId;  
        IF done THEN  
            LEAVE read_loop;  
        END IF;  
        -- 递归调用自身删除子节点的子节点  
        CALL DeleteChildren(childId);  
        -- 删除当前子节点  
        DELETE FROM system_menu WHERE id = childId;  
    DELETE FROM system_role_menu WHERE menu_id = childId;  
    END LOOP;  
    CLOSE cur;  
END  

SET SESSION max_sp_recursion_depth = 255;   
CALL DeleteChildren(4000);  
SET SESSION max_sp_recursion_depth = 0;