【问题标题】：How to get min max and avg from table in mysql with different rows?如何从具有不同行的mysql中的表中获取最小值最大值和平均值？
【发布时间】：2012-09-17 19:22:54
【问题描述】：

我有一个表格，记录如下。我想要的是单选查询，它按 mediaid 显示第一条记录最小值第二条记录平均值和第三条记录最大值组？

trans_id      playtime       mediaid(F.K.) 
--------      --------       -------------
1              32             2
2              65             2
3              45             3
4              55             4
5              60             3
6              78             2
7              45             4
8              35             3

结果应该是这样的

 playtime       mediaid(F.K.) 
   --------       -------------
    32             2             (Min value)
    58.33          2             (avg value)
    78             2             (Max value)
    35             3             (Min value)
    46.66          3             (avg value)
    60             3             (Max value)
    45             4             (Min value)
    50             4             (avg value)
    55             4             (max value)

这是我的真实查询给出的结果，但这不是由 medtitle 安排的

select  t.medTitle as 'Media',
    min(TIMESTAMPDIFF(SECOND,s.dmtViewStart,s.dmtViewEnd))platime
        from dbedetailing.tblmedia t
        left outer join dbedetailing.tbldoctormediatracktest s on s.dmtMedId = t.medId 
        GROUP BY t.medTitle
        union all
        select  t.medTitle as 'Media',
    avg(TIMESTAMPDIFF(SECOND,s.dmtViewStart,s.dmtViewEnd))platime
        from dbedetailing.tblmedia t
        left outer join dbedetailing.tbldoctormediatracktest s on s.dmtMedId = t.medId 
        GROUP BY t.medTitle
        union all
        select  t.medTitle as 'Media',
    max(TIMESTAMPDIFF(SECOND,s.dmtViewStart,s.dmtViewEnd))platime
        from dbedetailing.tblmedia t
        left outer join dbedetailing.tbldoctormediatracktest s on s.dmtMedId = t.medId 
        GROUP BY t.medTitle ;

这是我的真实查询给出的结果，但这不是由 medtitle 安排的

===数据库详细信息

== 表 tbldoctormediatracktest 的表结构

|------
|Column|Type|Null|Default
|------

    |//**dmtId**//|int(10)|No|
    |dmtDocId|int(10)|No|
    |dmtMedId|int(10)|No|
    |dmtViewingDate|datetime|No|
    |dmtViewStart|datetime|Yes|NULL
    |dmtViewEnd|datetime|Yes|NULL
    |dmaIsActive|enum('0', '1')|No|
    |insDate|datetime|No|
    |modDate|datetime|No|
    == Dumping data for table tbldoctormediatracktest
  Medid    dmtViewStart         dmtViewEnd
    |56|2012-08-24 11:41:14|2012-08-24 11:41:20
    |52|2012-08-24 11:41:24|2012-08-24 11:42:12
    |56|2012-08-24 11:41:14|2012-08-24 11:41:20
    |52|2012-08-24 11:41:24|2012-08-24 11:42:00
    |53|2012-08-25 12:32:27|2012-08-25 12:32:42
    |55|2012-08-27 06:48:51|2012-08-27 06:49:19
    |53|2012-08-27 06:49:25|2012-08-27 06:49:42
    |53|2012-08-28 02:56:16|2012-08-28 02:56:47
    |54|2012-08-28 02:57:58|2012-08-28 02:58:10
    |52|2012-08-28 05:48:14|2012-08-28 05:49:03
    |55|2012-08-28 07:16:00|2012-08-28 07:17:11
    |52|2012-08-22 04:03:00|2012-08-22 04:03:55
    |56|2012-08-28 07:16:00|2012-08-28 07:17:22
    |56|2012-08-23 09:00:00|2012-08-23 09:02:00
    |53|2012-08-16 04:00:00|2012-08-16 04:01:01
    |54|2012-08-20 12:33:00|2012-08-20 12:34:14
    |55|2012-08-16 04:00:20|2012-08-16 04:01:01
    |52|2012-08-20 12:31:00|2012-08-20 12:31:14
    |54|2012-08-20 12:33:14|2012-08-20 12:34:14
    |55|2012-08-20 12:48:00|2012-08-20 12:49:14
    |56|2012-08-20 12:33:00|2012-08-20 12:34:14
    |53|2012-08-20 12:43:00|2012-08-20 12:44:14
    |54|2012-08-20 12:33:00|2012-08-20 12:34:45
    |55|2012-08-20 12:33:00|2012-08-20 12:34:34
    |56|2012-08-20 12:33:00|2012-08-20 12:34:23
    |52|2012-08-20 12:33:00|2012-08-20 12:34:18
    |53|2012-08-20 12:33:00|2012-08-20 12:34:56
    |54|2012-08-20 12:33:00|2012-08-20 12:33:56
    |56|2012-08-20 12:33:00|2012-08-20 12:33:14
    |56|2012-08-20 12:33:00|2012-08-20 12:34:14



===Database dbedetailing

== Table structure for table tblmedia

|------
|Column|Type|Null|Default
|------
|//**medId**//|int(10)|No|
|medTitle|varchar(250)|No|
|medDesc|varchar(250)|No|
|medPath|varchar(250)|No|
|medType|int(10)|No|
|medSpeciality|int(10)|No|
|medProduct|int(10)|No|
|medIsActive|enum('0', '1')|No|
|insDate|datetime|No|
|modDate|datetime|No|
== Dumping data for table tblmedia

===数据库详细信息

== Dumping data for table tblmedia

|51|Tplanin
|52|Casfung
|53|Knee Surgery
|54|Doriglen
|55|Colymonas
|56|inem
|57|Casfungtest

【问题讨论】：

标签： mysql

【解决方案1】：

如果你想要在一行中的值，你可以这样做：

select max(playtime), min(playtime), avg(playtime)
from yourtable
group by mediaid;

如果您希望它们位于单独的行中，请使用 UNION ALL:

select max(playtime) playtime, mediaid, 'Max' Type
from yourtable
group by mediaid
union all
select min(playtime) playtime, mediaid, 'Min'
from yourtable
group by mediaid
union all
select avg(playtime) playtime, mediaid, 'Avg'
from yourtable
group by mediaid
order by mediaid, playtime;

见SQL Fiddle with Demo

编辑 #1，使用添加的示例数据：

select m.medTitle, 
  min(TIMESTAMPDIFF(SECOND, s.dmtViewStart, s.dmtViewEnd)) playtime
from tbldoctormediatracktest s
left join tblmedia m
  on s.MedId = m.MedId
group by m.medTitle
union all

select m.medTitle, 
  avg(TIMESTAMPDIFF(SECOND, s.dmtViewStart, s.dmtViewEnd)) playtime
from tbldoctormediatracktest s
left join tblmedia m
  on s.MedId = m.MedId
group by m.medTitle
union all

select m.medTitle, 
  max(TIMESTAMPDIFF(SECOND, s.dmtViewStart, s.dmtViewEnd)) playtime
from tbldoctormediatracktest s
left join tblmedia m
  on s.MedId = m.MedId
group by m.medTitle
order by medTitle,  playtime

见SQL Fiddle with Demo

【讨论】：

谢谢。给出结果但不分组。我已经更新了我的真实查询上部。
@ManishMalviya 如果您只运行Max() 中的一个查询，您会得到正确的结果吗？
是的，它可以工作。由 medTitle 安排。但我想要 MedTilte 的 goup
您可以编辑以发布您在数据库中的一些示例数据吗？
@ManishMalviya 你能发布另一个表dbedetailing.tblmedia的数据吗？