加入两个表,但如何显示所有结果?

时间:2011-03-09 16:50:27

标签: mysql sql join

我有两个这样的表结构:

episodes (
episode_id MEDIUMINT(8) UNSIGNED NOT NULL AUTO_INCREMENT,
episode_series_id MEDIUMINT(8) UNSIGNED NOT NULL DEFAULT '0',
episode_series_season TINYINT(2) UNSIGNED NOT NULL DEFAULT '0',
episode_series_episode SMALLINT(5) UNSIGNED NOT NULL DEFAULT '0',
episode_title VARCHAR(200) NOT NULL DEFAULT '',
PRIMARY KEY (episode_id),
KEY series_id (episode_series_id),
KEY episode_series_season (episode_series_season),
KEY episode_series_episode (episode_series_episode)
) ENGINE=MyISAM;

watchlist (
watchlist_id MEDIUMINT(8) UNSIGNED NOT NULL AUTO_INCREMENT,
watchlist_user_id MEDIUMINT(8) UNSIGNED NOT NULL DEFAULT '0',
watchlist_series_id MEDIUMINT(8) UNSIGNED NOT NULL DEFAULT '0',
watchlist_series_episode_id MEDIUMINT(8) UNSIGNED NOT NULL DEFAULT '0',
watchlist_status TINYINT(1) UNSIGNED NOT NULL DEFAULT '0',
PRIMARY KEY (watchlist_id),
KEY watchlist_series_episode_id (watchlist_series_episode_id),
KEY watchlist_series_id (watchlist_series_id)
) ENGINE=MyISAM;"

我想加入这两个,并显示所有结果。

这对我没有帮助:

SELECT e.*, w.* FROM episodes e, watchlist w WHERE e.episode_series_id='1' AND e.episode_series_season='1' AND w.watchlist_user_id='1'

我正在使用此查询,但与往常一样,它只显示匹配的列(剧集表格中有30多行,观察列表中有2行)

SELECT e.*,w.* FROM episodes e INNER JOIN watchlist w ON e.episode_id=w.watchlist_series_episode_id WHERE e.episode_series_id='1' AND e.episode_series_season='1' AND w.watchlist_user_id='1'

但它只显示2行(应该如此)。

episode_id  episode_series_id   episode_series_season   episode_series_episode  episode_title   watchlist_id    watchlist_user_id   watchlist_series_id watchlist_series_episode_id watchlist_status
1                 1                       1                      1                    Pilot            1                 1                    1                    1                        0
2                 1                       1                      2                 Paternity           2                 1                    1                    2                        0 

但是我希望显示所有匹配的结果(我想从这两个表中选择所有列,列出剧集,如果有一个来自监视列表的匹配我想要从watchlist列填充数据,否则它们应该为null)

我想得到这样的结果:

episode_id  episode_series_id   episode_series_season   episode_series_episode  episode_title   watchlist_id    watchlist_user_id   watchlist_series_id watchlist_series_episode_id watchlist_status
1                 1                       1                      1                    Pilot            1                 1                    1                    1                        0
2                 1                       1                      2                 Paternity           2                 1                    1                    2                        0 
3                 1                       1                      3                  whatever1         null             null                 null                 null                      null 
4                 1                       1                      4                  whatever2         null             null                 null                 null                      null 
5                 1                       1                      5                  whatever3         null             null                 null                 null                      null 

我不能把它放在一起。我怎么能这样做?

感谢。

4 个答案:

答案 0 :(得分:5)

这是LEFT JOIN的用途,而不是INNER JOIN

SELECT e.*,w.* 
FROM episodes e 
LEFT JOIN watchlist w 
   ON e.episode_id=w.watchlist_series_episode_id AND w.watchlist_user_id='1'
WHERE e.episode_series_id='1' 
AND e.episode_series_season='1' 
  • w.watchlist_user_id上的条件也必须出现在ON子句中。

答案 1 :(得分:0)

只需使用LEFT JOIN

SELECT * FROM episodes e 
LEFT JOIN watchlist w ON e.episode_id = w.watchlist_series_episode_id 
WHERE e.episode_series_id='1' 
AND e.episode_series_season='1' 
AND w.watchlist_user_id='1'

答案 2 :(得分:0)

将您的INNER JOIN更改为OUTER JOINLEFT JOINLEFT OUTER JOIN)。

答案 3 :(得分:0)

尝试左侧的连接剧集和右侧的观察列表....如果有的话,它将返回所有剧集和相应的观看列表...