Sql 查找最后一个连续行
我需要一些询问方面的帮助 我有一张简单的桌子:Sql 查找最后一个连续行,sql,mysql,Sql,Mysql,我需要一些询问方面的帮助 我有一张简单的桌子: CREATE TABLE `consecutiv` ( `id` int(11) NOT NULL auto_increment, `readVal` int(11) default NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM AUTO_INCREMENT=16 DEFAULT CHARSET=latin1; insert into `consecutiv`(`id`,`readVal`)
CREATE TABLE `consecutiv` (
`id` int(11) NOT NULL auto_increment,
`readVal` int(11) default NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=16 DEFAULT CHARSET=latin1;
insert into `consecutiv`(`id`,`readVal`) values (1,2),(2,2),(3,2),(5,3),(6,3),(7,3),(8,3),(9,4),(10,5),(11,6),(12,6),(13,2),(14,2),(15,6);
看起来像这样:
id readVal
1 2
2 2
3 2
5 3
6 3
7 3
8 3
9 4
10 5
11 6
12 6
13 2
14 2
15 6
我想获取给定readVal的最后一个连续行:
在上述示例中,这将是:
id:3表示readVal=2
id:8表示readVal=3
...
我尝试了以下查询:
SELECT consecutiv.id, consecutiv.readVal, c.id, c.readVal FROM consecutiv
JOIN consecutiv c ON consecutiv.id = c.id-1
WHERE consecutiv.readVal!=c.readVal ORDER BY consecutiv.id ASC
只要序列中没有丢失的id,它就可以工作。在上面的示例中,缺少id no 4,查询将不会返回预期结果
谢谢大家!
SELECT a.id, a.readVal
FROM consecutiv a
WHERE a.readVal !=
(SELECT b.readVal
FROM consecutiv b
WHERE b.id > a.id
ORDER BY id ASC
LIMIT 1)
ORDER BY a.id;
返回:
id | readval
----+---------
3 | 2
8 | 3
9 | 4
10 | 5
12 | 6
14 | 2
id | readval | nextreadval
----+---------+-------------
3 | 2 | 3
8 | 3 | 4
9 | 4 | 5
10 | 5 | 6
12 | 6 | 2
14 | 2 | 6
15 | 6 |
对于还需要最后一行的情况:
SELECT c.id, c.readVal, c.nextReadVal
FROM
(SELECT
a.id, a.readVal,
(SELECT b.readVal
FROM consecutiv b
WHERE b.id > a.id
ORDER BY id ASC
LIMIT 1) AS nextReadVal
FROM consecutiv a) AS c
WHERE readVal != nextReadVal OR nextReadVal IS NULL
ORDER BY c.id;
返回:
id | readval
----+---------
3 | 2
8 | 3
9 | 4
10 | 5
12 | 6
14 | 2
id | readval | nextreadval
----+---------+-------------
3 | 2 | 3
8 | 3 | 4
9 | 4 | 5
10 | 5 | 6
12 | 6 | 2
14 | 2 | 6
15 | 6 |
你说你期望readVal=2的id:3肯定这是13/14的最后一个连续结果吗?@rudi目前这是返回readVal=2的2个结果。编辑Oh I see I think by“我想获得给定readVal的最后一个连续行:”OP表示每对中的最后一个,而不是表中最后一对中的最后一个。在这种情况下,这看起来是最好的答案!对这正是我想要的。非常感谢。您确定结果中不需要id为15(val 6)的行吗?根据您对“最后一个连续行”的定义,它也应该返回,或者?(我也将为该案例添加一个查询)非常好,谢谢!我不需要自动取款机,但在其他地方可能有用!