我正在自己创建一个小项目，它有点像一个网站监控工具。 我有一个代理运行阅读网页，它对网站状态代码，内容检查和响应时间作出反应。
表格如下所示。
CREATE TABLE `data` (
`id` int(11) NOT NULL,
`check_id` int(11) NOT NULL,
`content_string_used` varchar(20) NOT NULL,
`content_check` enum('good','bad') NOT NULL,
`http_code` int(11) NOT NULL,
`total_time` varchar(5) NOT NULL,
`namelookup_time` varchar(5) NOT NULL,
`connect_time` varchar(5) NOT NULL,
`pretransfer_time` varchar(5) NOT NULL,
`starttransfer_time` varchar(5) NOT NULL,
`url` varchar(50) NOT NULL,
`time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
我要做的是选择特定支票的所有记录，例如
SELECT * FROM `data` WHERE `check_id` = 173;
现在这里变得棘手而且生病尽力解释。 行本身有一些重要的列。它的content_check和http_code。
我想要做的是将这两行作为分隔符对所有行进行分组，然后选择从第一个好行到最后一行的开始时间。
示例...
SELECT id, check_id, content_check, http_code, time from data WHERE `check_id` = 173;
结果
(15, 173, 'bad', 0, '2018-03-11 15:43:11'),
(23, 173,'bad', 0, '2018-03-11 15:44:11'),
(35, 173,'good', 0, '2018-03-11 15:45:11'),
(49, 173,'good', 0, '2018-03-11 15:46:11'),
(67, 173,'bad', 0, '2018-03-11 15:47:11'),
(85, 173,'bad', 0, '2018-03-11 15:48:11'),
(105, 173,'bad', 0, '2018-03-11 15:49:11'),
(125, 173,'good', 0, '2018-03-11 15:50:11'),
(145, 173,'bad', 0, '2018-03-11 15:51:11'),
(165, 173,'bad', 0, '2018-03-11 15:52:11');
id喜欢将这个返回到类似的查询，基本上将时间间隔的好/坏总结为某种分隔符。
(15, 'bad', 0, '2018-03-11 15:43:11', '2018-03-11 15:44:11'),
(35, 'good', 0, '2018-03-11 15:45:11', '2018-03-11 15:46:11'),
(67, 'bad', 0, '2018-03-11 15:47:11', 2018-03-11 15:49:11),
(125, 'good', 0, '2018-03-11 15:50:11', '2018-03-11 15:50:11'),
(145, 'bad', 0, '2018-03-11 15:51:11','2018-03-11 15:52:11'),
请帮助或指出我正确的方向。
答案 0 :(得分：0)
对于这样的事情有用的一个技巧是使用一对变量来跟踪最近的记录check_id和http_code，再加上第三个变量来表示其值的组号仅在check_id或http_code与前一记录的记录不同的记录上增加。例如，给出以下设置：
CREATE TABLE `data` (
`id` int(11) NOT NULL,
`check_id` int(11) NOT NULL,
`content_check` enum('good','bad') NOT NULL,
`http_code` int(11) NOT NULL,
`time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
insert into `data`
(`id`, `check_id`, `content_check`, `http_code`, `time`)
values
(15, 173, 'bad', 0, '2018-03-11 15:43:11'),
(23, 173, 'bad', 0, '2018-03-11 15:44:11'),
(35, 173, 'good', 0, '2018-03-11 15:45:11'),
(49, 173, 'good', 0, '2018-03-11 15:46:11'),
(67, 173, 'bad', 0, '2018-03-11 15:47:11'),
(85, 173, 'bad', 0, '2018-03-11 15:48:11'),
(105, 173, 'bad', 0, '2018-03-11 15:49:11'),
(125, 173, 'good', 0, '2018-03-11 15:50:11'),
(145, 173, 'bad', 0, '2018-03-11 15:51:11'),
(165, 173, 'bad', 0, '2018-03-11 15:52:11');
set @lastContentCheck = '';
set @lastHttpCode = '';
我可以编写以下查询，如上所述分配组号：
select
`id`,
`check_id`,
@groupNumber :=
case
when @lastContentCheck = `content_check` and @lastHttpCode = `http_code` then @groupNumber
else @groupNumber + 1
end as `GroupNumber`,
@lastContentCheck := `content_check` as `content_check`,
@lastHttpCode := `http_code` as `http_code`,
`time`
from
`data`,
(select @groupNumber := 0) as `gn`
where
`check_id` = 173
order by
`time`
此查询的输出为：
id check_id GroupNumber content_check http_code time
15 173 1 bad 0 2018-03-11 15:43:11
23 173 1 bad 0 2018-03-11 15:44:11
35 173 2 good 0 2018-03-11 15:45:11
49 173 2 good 0 2018-03-11 15:46:11
67 173 3 bad 0 2018-03-11 15:47:11
85 173 3 bad 0 2018-03-11 15:48:11
105 173 3 bad 0 2018-03-11 15:49:11
125 173 4 good 0 2018-03-11 15:50:11
145 173 5 bad 0 2018-03-11 15:51:11
165 173 5 bad 0 2018-03-11 15:52:11
此时，您可以通过简单地将上一个查询包裹起来，通过GroupNumber对其数据进行分组，从而获得所需的结果集。所以整件事情看起来像这样：
select
min(`id`) as `id`,
`check_id`,
`content_check`,
`http_code`,
min(`time`) as `EarliestTime`,
max(`time`) as `LatestTime`
from
(
select
`id`,
`check_id`,
@groupNumber :=
case
when @lastContentCheck = `content_check` and @lastHttpCode = `http_code` then @groupNumber
else @groupNumber + 1
end as `GroupNumber`,
@lastContentCheck := `content_check` as `content_check`,
@lastHttpCode := `http_code` as `http_code`,
`time`
from
`data`,
(select @groupNumber := 0) as `gn`
where
`check_id` = 173
order by
`time`
) as `GroupedData`
group by
`check_id`,
`GroupNumber`,
`content_check`,
`http_code`
order by
`GroupNumber`;
结果如你所愿：
id check_id content_check http_code EarliestTime LatestTime
15 173 bad 0 2018-03-11 15:43:11 2018-03-11 15:44:11
35 173 good 0 2018-03-11 15:45:11 2018-03-11 15:46:11
67 173 bad 0 2018-03-11 15:47:11 2018-03-11 15:49:11
125 173 good 0 2018-03-11 15:50:11 2018-03-11 15:50:11
145 173 bad 0 2018-03-11 15:51:11 2018-03-11 15:52:11
答案 1 :(得分：-1)
考虑到我不是MySQL的专家，我已经读过它不允许窗口函数，所以我试图在子选择中模拟它们。我不知道它是否允许公用表表达式，所以我尝试创建一个对所有数据库引擎都有效的SELECT语句。 试试这个：
create table table_test (id int, check_id int, content_check varchar(10), http_code int, [time] datetime)
insert into table_test values
(15, 173, 'bad', 0, '2018-03-11 15:43:11'),
(23, 173,'bad', 0, '2018-03-11 15:44:11'),
(35, 173,'good', 0, '2018-03-11 15:45:11'),
(49, 173,'good', 0, '2018-03-11 15:46:11'),
(67, 173,'bad', 0, '2018-03-11 15:47:11'),
(85, 173,'bad', 0, '2018-03-11 15:48:11'),
(105, 173,'bad', 0, '2018-03-11 15:49:11'),
(125, 173,'good', 0, '2018-03-11 15:50:11'),
(145, 173,'bad', 0, '2018-03-11 15:51:11'),
(165, 173,'bad', 0, '2018-03-11 15:52:11');
select t1.id,t3.content_check, t3.http_code ,t1.[time],t2.[time]
from (
select count(*) as rid, t1.id, t1.[time]
from table_test t1
join table_test t2
on t1.[time]>=t2.[time]
group by t1.id, t1.[time]
) t1
left join (
select count(*) as rid, t1.id, t1.[time]
from table_test t1
join table_test t2
on t1.[time]>=t2.[time]
group by t1.id, t1.[time]
) t2
on t1.rid=t2.rid-1
join table_test t3
on t1.id=t3.id
where t1.rid%2<>0