MySQL GROUP by field maximum record [this blog contains pictures]

Requirements: Get the record information that is grouped by table1_id and age maximum, i.e. 2, 3, 5 method One:select * FROM (SELECT * from Table2 ORDER BY age DESC) as AG Roup by a.table1_id Method two:select a.* from Table2 as a where age = (select Max (age) Fromtable2 where A.table1_id=tab le1_id) method Three:select A.* from Table2 as a where isn't exists (SELECT * Fromtable2 where table1_id=a.table1_id and age >a.age) method Four:select A.* from Table2 as a where exists (select COUNT (*) Fromtable2 where table1_id=a.table1_id a nd age>a.age havingcount (*) =0)

MySQL GROUP by field maximum record [this blog contains pictures]