我正在处理制造成本和尚未完成的制造价值（“在制品净值”）。SQL是直接的算术，但如果分母中有负号（减法），则查询不会得出值。数据库列：

A = Material issued cost
B = Miscellaneous cost adds 
C = Labor
D = Overhead
E = Setup cost
F = Scrap cost
G = Received cost (cost of assemblies completed already)

H = Original Quantity ordered
I = Quantity deviation
J = Quantity split from order
K = Quantity received (number of assemblies completed already)

净在制品成本等于总剩余成本除以总剩余数量。因此，简而言之，我只是想这样做：

select (A + B + C + D + E - F - G) / (H + I - J - K) from MyTable

减法在分子中运行良好，但一旦我在分母中做减法，查询就不会返回任何值（空白）。我已经尝试过类似的方法：

select (A + B + C + D + E - F - G) / (H + I - (J + K)) from MyTable
select (A + B + C + D + E - F - G) / (H + I + (-J) + (-K)) from MyTable
select (A + B + C + D + E - F - G) / (H + I + (J * -1) + (K * -1)) from MyTable

这些都不起作用。只是想知道是否有人在IBM的DB2数据库上遇到过这个问题？谢谢。