mysql - 创建删除触发器时的MySQL语法错误

Question

我在数据库中创建触发器时遇到问题。这个想法是，当从播放列表中删除歌曲时，相应的行将从表playlistcancion中删除。触发器的思想是从播放列表的总时间中删除已删除歌曲的时间。

view name: pycs (shows songs of corresponding playlists)
column name | SongID | playlistID | Playlist | songName | Duration
data type   | INT    | INT        | varchar  | varchar  | TIME 

table name: playlistcancion (keeps track of which songs are in which playlists)
column name | songID | playlistID 
data type   | INT    | INT   

table name: playlists (playlist data and creators userID)
column name | playlistID| userID  | Followers  | Title  | TotalDuration
data type   | INT       | INT     | INT        | varchar| TIME 

这是我的触发器查询:

CREATE TRIGGER remove_time
AFTER DELETE ON playlistcancion
FOR EACH ROW 
    DECLARE dur TIME;
    SELECT Duration INTO dur FROM pycs WHERE playlistID = OLD.playlistID AND songID = OLD.songID;
    UPDATE playlists SET TotalDuration = SEC_TO_TIME(TIME_TO_SEC(TotalDuration) - TIME_TO_SEC(dur))
    WHERE playlistID = OLD.playlistID;

我得到的错误是:
MySQL说:＃1064-'DECLARE dur TIME附近的语法有问题；在第1行的pycs中选择持续时间INTO dur从pycs处playlisID = OLD.pla'
我正在使用phpMyAdmin创建触发器。
提前致谢。

Answer 1

添加BEGIN和END解决了您遇到的错误。

CREATE TRIGGER remove_time
AFTER DELETE ON playlistcancion
FOR EACH ROW BEGIN
    DECLARE dur TIME;
    SELECT Duration INTO dur FROM pycs WHERE playlistID = OLD.playlistID AND songID = OLD.songID;
    UPDATE playlists SET TotalDuration = SEC_TO_TIME(TIME_TO_SEC(TotalDuration) - TIME_TO_SEC(dur))
    WHERE playlistID = OLD.playlistID;
    END;

如果您面临更多问题，最好使用触发器中涉及的所有表的插入脚本发布。