请问可以根据两个字段进行group by吗？

Question

+--------+--------+
|doc     |drcr    |
+--------+--------+
|1       |10      |
|1       |13      |
|2       |3       |
|2       |5       |
+--------+--------+
select doc,sum(drcr) from table1 broup by doc+--------+--------+
|doc     |drcr    |
+--------+--------+
|1       |23      |
|2       |8       |
+--------+--------+

Answer 1

不是这个意思，我要得到这样的数据
+--------+--------+--------+
|doc     |drcr    |   amt  |
+--------+--------+--------+
|1       |1       |   4    |
|1       |1       |   7    |
|1       |2       |   7    |
|1       |2       |   2    |
+--------+--------+--------+
结果
+--------+--------+--------+
|doc     |drcr    |   amt  |
+--------+--------+--------+
|1       |1       |   11   |
|1       |2       |   9    |
+--------+--------+--------+

Answer 2

select doc,drcr,sum(amt) from table1 broup by doc,drcr