我有下表：
id value acc_no
-----------------
1 12 1
2 14 1
3 15 1
4 10 2
5 16 2
6 19 1
7 7 3
8 24 2
预期输出
id value acc_no result
------------------------------
1 12 1 12(current row values of acc_no=1)
2 14 1 2(14 (current row values)-12(previous row value of acc_no=1))
3 15 1 1(15-14)
4 10 2 10(current row values of acc_no=2)
5 16 2 6(16 (current row values)-12(previous row value of acc_no=2))
6 19 1 …