Question

我有多个表，每个表都有FK关系，可以将它们相互连接。我需要使用某些表中的详细信息创建数据透视表。

Region Table
Region_ID|Region_Description

State Table
State_ID|State_Description|Region_ID_FK

Order Table
Order_ID|Order_Date|State_ID_FK

Category Table
Category_ID|Category|Description|Order_ID_FK

我使用基于FK的自然连接加入所有表。

我需要确定每个地区每个类别的订单数量。

结果表应如下所示：

 Category|Region1|Region2|Region3|Total
 Sporting    1       0      3      4
 ETC         0       2      1      3

Answer 1

SELECT c.Category,
       COUNT( CASE r.Region_ID WHEN 1 THEN 1 ELSE NULL END ) AS Region1,
       COUNT( CASE r.Region_ID WHEN 2 THEN 1 ELSE NULL END ) AS Region2,
       COUNT( CASE r.Region_ID WHEN 3 THEN 1 ELSE NULL END ) AS Region3,
       COUNT( CASE r.Region_ID WHEN 4 THEN 1 ELSE NULL END ) AS Region4 
FROM   REGION r
       INNER JOIN
       STATE s
       ON (r.Region_ID = s.Region_ID_FK)
       INNER JOIN
       ORDER o
       ON (s.State_ID = o.State_ID_FK)
       INNER JOIN
       CATEGORY c
       ON (o.Order_ID = c.Order_ID_FK)
GROUP BY c.Category

初学者Oracle 11g SQL - 通过连接多个表创建数据透视表

1 个答案: