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# mysql分组取最大(最小、最新、前N条)条记录

2017年12月31日 20:02 阅读 945 views 次

``````
create table tb(name varchar(10),val int,memo varchar(20))
insert into tb values('a',    2,   'a2')
insert into tb values('a',    1,   'a1')
insert into tb values('a',    3,   'a3')
insert into tb values('b',    1,   'b1')
insert into tb values('b',    3,   'b3')
insert into tb values('b',    2,   'b2')
insert into tb values('b',    4,   'b4')
insert into tb values('b',    5,   'b5')
``````

 name val memo a 2 a2 a 1 a1 a 3 a3 b 1 b1 b 3 b3 b 2 b2 b 4 b4 b 5 b5

## 按name分组取val最大的值所在行的数据

``````
select a.* from tb a where val = (select max(val) from tb where name = a.name) order by a.name
``````

``````
select a.* from tb a where not exists(select 1 from tb where name = a.name and val > a.val)
``````

``````
select a.* from tb a,(select name,max(val) val from tb group by name) b where a.name = b.name and a.val = b.val order by a.name
``````

``````
select a.* from tb a inner join (select name , max(val) val from tb group by name) b on a.name = b.name and a.val = b.val order by
``````

``````
select a.* from tb a where 1 > (select count(*) from tb where name = a.name and val > a.val ) order by a.name
``````

 name val memo a 3 a3 b 5 b5

## 按name分组取val最小的值所在行的数据

``````
select a.* from tb a where val = (select min(val) from tb where name = a.name) order by a.name
``````

``````
select a.* from tb a where not exists(select 1 from tb where name = a.name and val < a.val)
``````

``````
select a.* from tb a,(select name,min(val) val from tb group by name) b where a.name = b.name and a.val = b.val order by a.name
``````

``````
select a.* from tb a inner join (select name , min(val) val from tb group by name) b on a.name = b.name and a.val = b.val order by a.name
``````

``````
select a.* from tb a where 1 > (select count(*) from tb where name = a.name and val < a.val) order by a.name
``````

 name val memo a 1 a1 b 1 b1

## 按name分组取第一次出现的行所在的数据

sql如下：

``````
select a.* from tb a where val = (select top 1 val from tb where name = a.name) order by a.name
``````

 name val memo a 2 a2 b 1 b1

## 按name分组随机取一条数据

sql如下：

``````
select a.* from tb a where val = (select top 1 val from tb where name = a.name order by newid()) order by a.name
``````

 name val memo a 1 a1 b 3 b3

## 按name分组取最小的两个(N个)val

``````
select a.* from tb a where 2 > (select count(*) from tb where name = a.name and val < a.val ) order by a.name,a.val
``````

``````
select a.* from tb a where val in (select top 2 val from tb where name=a.name order by val) order by a.name,a.val
``````

``````
select a.* from tb a where exists (select count(*) from tb where name = a.name and val < a.val having Count(*) < 2) order by a.name
``````

 name val memo a 1 a1 a 2 a2 b 1 b1 b 2 b2

## 按name分组取最大的两个(N个)val

``````
select a.* from tb a where 2 > (select count(*) from tb where name = a.name and val > a.val ) order by a.name,a.val
``````

``````
select a.* from tb a where val in (select top 2 val from tb where name=a.name order by val desc) order by a.name,a.val
``````

``````
select a.* from tb a where exists (select count(*) from tb where name = a.name and val > a.val having Count(*) < 2) order by a.name
``````

 name val memo a 3 a3 a 2 a2 b 5 b5 b 4 b4

### 布施恩德可便相知重

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