要求：获得按 table1_id 分组，并且取得 table2 中 age 最大的记录信息。 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： ...       MySQL, 分组, 最大值阅读全文