discuz pre_forum_postposition表说明 - 一种新的自增字段实例

pre_forum_postposition

抢楼帖时会用到

CREATE TABLE `pre_forum_postposition` (
`tid` mediumint(8) unsigned NOT NULL,
`position` int(10) unsigned NOT NULL AUTO_INCREMENT,
`pid` int(10) unsigned NOT NULL,
PRIMARY KEY (`tid`,`position`),
KEY `pid` (`pid`)
) ENGINE=MyISAM DEFAULT CHARSET=gbk

主键是`tid`,`position`， 当插入   insert into pre_forum_postposition set tid=1128898, pid=2814945;

`position` 以 `tid` `pid` 为区分在该条件下自增

| 1128898 | 38 | 2811923 |
| 1128898 | 39 | 2814943 |

insert into pre_forum_postposition set tid=1128898, pid=2814945;

| 1128898 | 39 | 2814943 |
| 1128898 | 40 | 2814945 |