對一個表中的行求和，然后將其移至另一表

Question

如何對一個表中的行求和（基於選定的critiria）並將結果移至另一表。

我有一個與項目內成本相關的表：

表“費用”：

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

我想將每個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

非常感謝

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

我不會存儲它，因為一旦Costs發生任何變化，那么CostCategories將過時，相反，我將創建一個視圖，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;

現在，您可以引用該視圖，而不必引用該表，並且“ Planned和Done總數將始終是最新的。