CREATE TABLE IF NOT EXISTS `tweets_comment_tbl` (
`tweet_comment_id` int(12) NOT NULL AUTO_INCREMENT,
`tweet_id` int(12) NOT NULL,
`tweets_comment` text NOT NULL,
`created` int(12) NOT NULL,
`changed` int(12) NOT NULL,
`uid` int(12) NOT NULL,
`userip` varchar(20) NOT NULL,
`referer` text NOT NULL,
`status` int(2) NOT NULL DEFAULT '1',
PRIMARY KEY (`tweet_comment_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=6 ;
--
-- Dumping data for table `tweets_comment_tbl`
--
INSERT INTO `tweets_comment_tbl` (`tweet_comment_id`, `tweet_id`, `tweets_comment`, `created`, `changed`, `uid`, `userip`, `referer`, `status`) VALUES
(1, 1, 'COMMENT USER1', 1319395671, 1319395671, 3, '127.0.0.1', 'http://localhost/drupal_tutorial/', 1),
(2, 2, 'comment admin user', 1319395724, 1319395724, 1, '127.0.0.1', 'http://localhost/drupal_tutorial/node', 1),
(3, 2, 'USER COMMENTING HIS COMMENT', 1319395838, 1319395838, 3, '127.0.0.1', 'http://localhost/drupal_tutorial/', 1),
(4, 2, 'ADMIN COMMENTING FOR HIS COMMENT', 1319395865, 1319395865, 1, '127.0.0.1', 'http://localhost/drupal_tutorial/node', 1),
(5, 2, 'dddCOMMENT USER1: ADMIN DOING COMMENT FOR STATUS UPDATE1', 1319395905, 1319395905, 1, '127.0.0.1', 'http://localhost/drupal_tutorial/node', 1);
我的第二個表右連接查詢返回空值的記錄
CREATE TABLE IF NOT EXISTS `tweets_tbl` (
`tweet_id` int(11) NOT NULL AUTO_INCREMENT,
`tweets` text NOT NULL,
`created` int(12) NOT NULL,
`changed` int(12) NOT NULL,
`uid` int(12) NOT NULL,
`userip` varchar(20) NOT NULL,
`referer` text NOT NULL,
`status` int(2) NOT NULL DEFAULT '1',
PRIMARY KEY (`tweet_id`),
KEY `tweet_id` (`tweet_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;
--
-- Dumping data for table `tweets_tbl`
--
INSERT INTO `tweets_tbl` (`tweet_id`, `tweets`, `created`, `changed`, `uid`, `userip`, `referer`, `status`) VALUES
(1, 'STATUS UPDATE 1', 1319395633, 1319395633, 1, '127.0.0.1', 'http://localhost/drupal_tutorial/node', 1),
(2, 'Status update user1', 1319395696, 1319395696, 3, '127.0.0.1', 'http://localhost/drupal_tutorial/node', 1);
試圖連接查詢
SELECT ut.picture as picture, tct.tweet_id as tweet_id, tct.tweets_comment as tweets_comment, tct.changed
FROM tweets_comment_tbl tct
RIGHT JOIN users as ut ON tct.uid=ut.uid AND tct.tweet_id=2 AND tct.status = 1
order by tct.created desc
回報記錄,上面的查詢
picture tweet_id tweets_comment changed
1 COMMENT USER1 1319395671
NULL NULL NULL
picture-1.png NULL NULL NULL
其實我的預期是
爲什麼查詢已經返回NULL記錄,我不知道我在連接查詢中犯了錯誤。
'right outer join'通過設計生成空值。如果你不想要空值(我建議你不要),那麼就避免外連接。 – onedaywhen
如何在沒有連接的情況下完全填充以上輸出 –