mysql存储过程中不显示错误消息

Question

我正在尝试验证某些内容，但它始终会返回成功结果。我想知道我的代码有什么问题。

      INSERT INTO playlist_details (playlist_id,filename,image_id,transition,timeframe,userid,update_date)
    VALUES (i_playlistid,i_filename,i_imageid, i_transition, i_time, i_userid,i_date);

    SELECT booking_id INTO v_booking_id FROM staging_table WHERE playlist_id = i_playlistid LIMIT 1;

    SELECT num_of_spots INTO v_spots FROM booking_sum WHERE booking_id = v_booking_id;

    SET v_allowed_time = v_spots * 30;

    IF ((SELECT SUM(timeframe) FROM playlist_details WHERE playlist_id = i_playlistid) > v_allowed_time) THEN

    SET o_success = FALSE;
    SET o_message = 'You exceeded the time allowed with your booking';

     SELECT playlist_id,filename,image_id,transition,timeframe,userid FROM playlist_details
    WHERE userid = i_userid;

    ELSE

     SELECT playlist_id,filename,image_id,transition,timeframe,userid FROM playlist_details
    WHERE userid = i_userid;

    SET o_success = TRUE;
    SET o_message = 'Success';

    END IF;