Mysql按字段分组取最大值记录

Posted 2023-04-03

select a.* from table2 as a where age = (select max(age) from table2 where a.table1_id=table1_id)sql语句解答一下，重要讲解后面的where条件 a.table1_id=table1_id

参考技术A 其实这个方法有问题应该这样写
select table1_id,max(age) age from table2 group by table1_id
你的where条件 a.table1_id=table1_id是判断当前table1_id的值age是不是最大的本回答被提问者和网友采纳

MySql按字段分组取最大值记录 [此博文包含图片]

 

要求：获得按table1_id分组，并且age最大的记录信息，即2、3、5条

 

 

方法一：

select * from (select * from table2 order by age desc) as a group by a.table1_id

 

方法二：

select a.* from table2 as a where age = (select max(age) from table2 where a.table1_id=table1_id)

 

方法三：

select a.* from table2 as a where not exists (select * from table2 where table1_id=a.table1_id and age>a.age)

 

方法四：

select a.* from table2 as a where exists (select count(*) from table2 where table1_id=a.table1_id and age>a.age having count(*)=0)