如何连接2个外键列？

Question

我有2桌电影和演员。 电影表具有2列，分别是actor 1和actor 2，它们是具有所有actor的Actor表的外键。

在SELECT查询中，我想将actor 1和actor 2都显示为一列示例（Actor1，Actor2）

电影桌

Id     MovieName   Producer   Actor1    Actor2
1         X-man      prod1     1           2
2         Ant        Prod2     3           1

演员表

Id  ActorName
1     Sam
2     Jhon
3     Brick

我想要的结果

Id     MovieName   Producer      Actors
1         X-man      prod1     Sam , Jhon
2         Ant        Prod2     Brick,Sam

Answer 1

要按要求回答您的问题，您需要两次连接到Actor表，类似这样的select Movie.id, MovieName, Producer, a1.Name+', '+a2.name as 'Actors' from Movie INNER JOIN Actor a1 on Actor1 = a1.id INNER JOIN Actor a2 on Actor2 = a2.id

但是，正如注释中指出的那样，理想情况下，您应该对数据进行更多的规范化，以便表结构类似于

CREATE TABLE Movie(
    Id int PRIMARY KEY,
    MovieName nvarchar(50),
    Producer nvarchar(50)
    );

CREATE TABLE Actor(
    Id int PRIMARY KEY,
    Name nvarchar(50)
    );

CREATE TABLE MovieActor(
    Id int PRIMARY KEY
    ActorId int,
    MovieId int);

Answer 2

您可以尝试以下方法：

Declare @movie table (id int, moviename varchar(50),producer varchar(50),actor1 int, actor2 int)

Declare @Actor table (Id int, Actorname varchar(50))

Insert into @movie values (1,'X-Man','Prod1',1,2)
Insert into @movie values (2,'ANt Man','Prod2',3,1)

insert into @Actor values (1,'Sam')
insert into @Actor values (2,'Jhon')
insert into @Actor values (3,'Brick')


select * from @Actor

select a.id,a.moviename,a.producer,b.Actorname + ',' + c.Actorname as actors from @movie a

join  @Actor b

on a.actor1=b.Id  

join @Actor c on c.Id=a.actor2