SQL server求sum时的判断
我现在想取C的和 也就是 sum(c) 条件是当A相同时取最大的B那一行的C作为C的值求和，
也就是
0100 7
0101 1
0102 1
0105 9
这四列的C的值求和 请问一下sql要怎么写
select sum(C) from (select A,max(B) B from table group by A) t1 , table t2 where t1.A = t2.A and t1.B = t2.B
select sum(C) from (select A,max(B) B from table group by A) t1 , table t2 where t1.A = t2.A and t1.B = t2.B