Question

我有2张桌子 Maintable 和 Secondtable

在第二个表中是一列Maintable_ID和Price。

我在Workbench中建立了一个像这样的视图：

CREATE VIEW test AS 
SELECT Maintable.ID as ID,
       Maintable.Name as Name,
       Maintable.Date as Date,
       Secondtable.Price as Price,
From maintable

LEFT JOIN secondtable
ON Maintable.ID=Secondtable.Maintable_ID

我曾想过要做类似的事情：

SUM(Price) as GPrice FROM Secondtable WHERE Maintable.ID=Secondtable.Maintable_ID

我怎样才能找到Secondtable中所有项目的总价格，其中Secondtable.Maintable_ID = Maintable.ID

感谢您的帮助。

Answer 1

试试这个..

CREATE VIEW test AS 
SELECT Maintable.ID as ID,
       Maintable.Name as Name,
       Maintable.Date as Date,
       sum (Secondtable.Price) as GPrice,
From maintable

LEFT JOIN secondtable
ON Maintable.ID=Secondtable.Maintable_ID
Group by 
      Maintable.ID as ID,
       Maintable.Name as Name,
       Maintable.Date as Date

Answer 2

你走在正确的轨道上，你只是错过了一个group by条款：

CREATE VIEW test AS 
SELECT Maintable.ID as ID,
       Maintable.Name as Name,
       Maintable.Date as Date,
       s.Sum_Price as Price,
FROM   maintable m
LEFT JOIN (SELECT   Maintable_ID, SUM(Price) AS Sum_Price)
           FROM     secondtable
           GROUP BY Maintable_ID) s
       ON m.ID=s.Maintable_ID

Answer 3

您可以尝试以下查询

  SELECT Secondtable.Maintable_ID ,
  SUM(Secondtable.Price) as GPrice,
  From Secondtable inner join Maintable ON Secondtable.Maintable_ID=Maintable.ID
   GROUP BY Secondtable.Maintable_ID

如何在一个视图中从SQL中的另一个表求和？

3 个答案: