计算同一列中两个值的差异

Question

当我将具有相同CATEGORY值的记录组合在一起时，我想找到差异（利润和损失）（例如，将组合A＆＃39;并且将组合C＆＃39;）。

Answer 1

我认为你想要条件聚合：

A["b"]

Answer 2

Select category, buy.amt-sell.amt ProfitorLoss
from
(SELECT sum(price*quantity) amt, Category
  FROM yourtable
 WHERE side = 'BUY'
GROUP BY Category) buy,
(SELECT sum(price*quantity) amt, Category
  FROM yourtable
 WHERE side = 'SELL'
GROUP BY Category) sell
where buy.category = sell.category