MySql按字段分组取最大值记录
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MySql按字段分组取最大值记录
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)