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MySql按字段分组取最大值记录 [此博文包含图片]

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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)

MySql按字段分组取最大值记录 [此博文包含图片]