对一个表中的行求和，然后将其移至另一表

Question

如何对一个表中的行求和（基于选定的critiria）并将结果移至另一表。

我有一个与项目内成本相关的表：

表“费用”：

id| CostName |ID_CostCategory| PlanValue|DoneValue
-------------------------------------------------------
1 | books    |1              |100       |120
2 | flowers  |1              |90        |90
3 | car      |2              |150       |130
4 | gas      |2              |50        |45

我想将每个ID_CostCategory的“ DoneValue”之和放入表“ CostCategories”中

表格“ CostCategories”：

id|name |planned|done
------------------------
1 |other|190    |takes the sum from above table
2 |car  |200    |takes the sum from above table

非常感谢

Answer 1

INSERT INTO CostCategories(id,name,planned,done)
SELECT ID_CostCategory, CostName, SUM(PlanValue), SUM(DoneValue)
FROM costs GROUP BY ID_CostCategory, CostName

Answer 2

我不会存储它，因为一旦Costs发生任何变化，那么CostCategories将过时，相反，我将创建一个视图，例如：

CREATE VIEW CostCategoriesSum
AS
SELECT  CostCategories.ID,
        CostCategories.Name,
        SUM(COALESCE(Costs.PlanValue, 0)) AS Planned,
        SUM(COALESCE(Costs.DoneValue, 0)) AS Done
FROM    CostCategories
        LEFT JOIN Costs
            ON Costs.ID_CostCategory = CostCategories.ID
GROUP BY CostCategories.ID, CostCategories.Name;

现在，您可以引用该视图，而不必引用该表，并且“ Planned和Done总数将始终是最新的。