***********************根据你的补充补充回答：***********************select a,sum(b) as 记录数,max(c) as cfrom 表名group by a;---以上，希望对你有所帮助。
select a,sum(b) as 记录数,c from table group by a,c
select a,sum(b),c from table group by a,b
select a,sum(b),c from 表 group by a,c