计算同一列中两个值的差异

Question

当我将记录与相同的CATEGORY值组合时，我想找到差异（利润和损失）（例如，A将被组合并且C将被组合）。

Answer 1

我想你想要条件聚合：

select category,
       sum(iif(side = "BUY", - quantity * price, quantity * price)) as net
from t
where side in ("BUY", "SELL")  -- may not be necessary
group by category;

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