Question

我是SQL编程的新手，有以下场景。我有三个表彼此链接为 -

ForceInstance

ForceInstanceID (PK)
ForceID (FK to Force)
Description
CreatedBy
CreatedOn

强制

ForceID (PK)
ForceTypeID (FK to ForceType)
Description
CreatedBy
CreatedOn`

ForceType指令

ForceTypeID (PK)
Description

我想连接三个表，我尝试了这个查询 -

Select * from ForceInstance FI inner join 
              Force F inner join
              ForceType FT
          on  FI.ForceID = F.ForceID
          and F.ForceTypeID = FT.ForceTypeID

但无法实现任何目标。我是SQL的新手，想知道如何实现这个目标。

Answer 1

Select * from ForceInstance FI 
inner join Force F on  FI.ForceID = F.ForceID
inner join ForceType FT on F.ForceTypeID = FT.ForceTypeID

Answer 2

SELECT    * 
FROM      ForceInstance FI 
          INNER JOIN Force F 
              ON FI.ForceID = F.ForceID 
          INNER JOIN ForceType FT
              ON F.ForceTypeID = FT.ForceTypeID

Answer 3

 Select * from ForceInstance FI  join 
              Force F 
              on  FI.ForceID = F.ForceID
             JOIN ForceType FT           
               on F.ForceTypeID = FT.ForceTypeID

内部连接由外键链接的三个表

3 个答案: