SQL Server - 无效表

Question

我对 SQL 还很陌生，我不明白为什么在建立外键时收到错误消息，因为我收到错误消息说目标表无效。

下面是 SQL 代码，任何关于如何修复的建议都会很棒！ :)

出现关于 tblFilms 和 tblCinemaScreens 的错误。

CREATE TABLE tblCustomer (
    CustomerID int,
    CustomerSurname NVARCHAR(25),
    CustomerForename NVARCHAR(20),
    CustomerAge int,
    CustomerPhoneNumber NVARCHAR(12),
    CustomerEmailAddress NVARCHAR(100),
    CONSTRAINT PK_tblCustomer PRIMARY KEY CLUSTERED (CustomerID)
    )
    GO

CREATE TABLE tblBookings (
    BookingID int,
    FilmShowings TIME,
    PriceOfFilm MONEY,
    DateOfBooking DATE,
    FilmID int,
    CinemaScreenID int,
    CustomerID int,
    CONSTRAINT PK_tblBookings PRIMARY KEY CLUSTERED (BookingID),
    CONSTRAINT FK_FilmID FOREIGN KEY (FilmID) REFERENCES tblFilms(FilmID),
    CONSTRAINT FK_CustomerID FOREIGN KEY (CustomerID) REFERENCES tblCustomer(CustomerID)
    )
    GO

CREATE TABLE tblFilms (
    FilmID int,
    FilmName VARCHAR(100),
    FilmDuration int,
    AgeRating VARCHAR(3),
    CriticScore int,
    FilmDescription NVARCHAR(300),
    FilmGenre NVARCHAR(20),
    FilmStartScreeningDate DATE,
    FlimEndScreeningDate DATE,
    CinemaScreenID int,
    CONSTRAINT PK_tblFilms PRIMARY KEY CLUSTERED (FilmID),
    CONSTRAINT FK_tblFilms FOREIGN KEY (CinemaScreenID) REFERENCES tblCinemaScreens(CinemaScreenID)
    )
    GO

CREATE TABLE tblCinemaScreens (
    CinemaScreenID int, 
    CinemaScreenType NVARCHAR(10),
    NumberOfSeats int,
    FilmID int,
    CONSTRAINT PK_tblCinemaScreens PRIMARY KEY CLUSTERED (CinemaScreenID),
    CONSTRAINT FK_tblCinemaScreens FOREIGN KEY (FilmID) REFERENCES tblFilms(FilmID)
    )
    GO

Answer 1

电影屏幕表不需要电影 ID，您需要在使用 FK 引用它们之前创建表

CREATE TABLE tblCinemaScreens (
    CinemaScreenID int, 
    CinemaScreenType NVARCHAR(10),
    NumberOfSeats int,
    FilmID int,
    CONSTRAINT PK_tblCinemaScreens PRIMARY KEY CLUSTERED (CinemaScreenID)
    GO

CREATE TABLE tblFilms (
    FilmID int,
    FilmName VARCHAR(100),
    FilmDuration int,
    AgeRating VARCHAR(3),
    CriticScore int,
    FilmDescription NVARCHAR(300),
    FilmGenre NVARCHAR(20),
    FilmStartScreeningDate DATE,
    FlimEndScreeningDate DATE,
    CinemaScreenID int,
    CONSTRAINT PK_tblFilms PRIMARY KEY CLUSTERED (FilmID),
    CONSTRAINT FK_tblFilms FOREIGN KEY (CinemaScreenID) REFERENCES tblCinemaScreens(CinemaScreenID)
    )
    GO

CREATE TABLE tblCustomer (
    CustomerID int,
    CustomerSurname NVARCHAR(25),
    CustomerForename NVARCHAR(20),
    CustomerAge int,
    CustomerPhoneNumber NVARCHAR(12),
    CustomerEmailAddress NVARCHAR(100),
    CONSTRAINT PK_tblCustomer PRIMARY KEY CLUSTERED (CustomerID)
    )
    GO

CREATE TABLE tblFilms (
    FilmID int,
    FilmName VARCHAR(100),
    FilmDuration int,
    AgeRating VARCHAR(3),
    CriticScore int,
    FilmDescription NVARCHAR(300),
    FilmGenre NVARCHAR(20),
    FilmStartScreeningDate DATE,
    FlimEndScreeningDate DATE,
    CinemaScreenID int,
    CONSTRAINT PK_tblFilms PRIMARY KEY CLUSTERED (FilmID),
    CONSTRAINT FK_tblFilms FOREIGN KEY (CinemaScreenID) REFERENCES tblCinemaScreens(CinemaScreenID)
    )
    GO

Answer 2

您正试图在创建表之前为其创建外键。注释掉 create table 语句中出现错误的行并创建表。创建表后，创建您需要的缺少的外键，如下所示：

alter table tblFilms
add CONSTRAINT FK_tblFilms FOREIGN KEY (CinemaScreenID) REFERENCES tblCinemaScreens(CinemaScreenID)

alter table tblBookings
add CONSTRAINT FK_FilmID FOREIGN KEY (FilmID) REFERENCES tblFilms(FilmID)

Answer 3

答案是他们不应该有直接的关系
一部电影在 0 个或多个屏幕上放映

你需要一个连接表

rblFilmCinema  
filmID   fk to tblFilms
screenID fk to tblCinemaScreens  

composite PK on filmID, screenID

Answer 4

我会改变一些架构，给自己更多的灵活性。我会假设一部电影可以在多个电影院屏幕上，所以我会从tblFilms 中取出CinemaScreenID 并删除外键。您还可以从tblBookings 中删除FilmID，因为您已经拥有CinemaScreenID，它已经拥有FilmID.. 另一件要考虑的事情可能是在同一个CinemaScreen 上拥有多部电影，这将是另一个名为@987654328 的表格@ 并且您会将 CinemaScreenFilmID 放在 tblBookings 上

CREATE TABLE tblFilms (
    FilmID int,
    ...
    CONSTRAINT PK_tblFilms PRIMARY KEY CLUSTERED (FilmID),
    )
    GO

CREATE TABLE tblCustomer (
    CustomerID int,
    ...
    CONSTRAINT PK_tblCustomer PRIMARY KEY CLUSTERED (CustomerID)
    )
    GO

CREATE TABLE tblBookings (
    BookingID int,
    CinemaScreenID int,
    CustomerID int,
    ...
    CONSTRAINT PK_tblBookings PRIMARY KEY CLUSTERED (BookingID),
    CONSTRAINT FK_CinemaScreenID  FOREIGN KEY (CinemaScreenID ) REFERENCES tblCinemaScreens(CinemaScreenID),
    CONSTRAINT FK_CustomerID FOREIGN KEY (CustomerID) REFERENCES tblCustomer(CustomerID)
    )
    GO


CREATE TABLE tblCinemaScreens (
    CinemaScreenID int, 
    FilmID int,
    ...
    CONSTRAINT PK_tblCinemaScreens PRIMARY KEY CLUSTERED (CinemaScreenID),
    CONSTRAINT FK_tblCinemaScreens FOREIGN KEY (FilmID) REFERENCES tblFilms(FilmID)
    )
    GO

选项 B（首选）

CREATE TABLE tblCustomer (
    CustomerID int,
    ...
    CONSTRAINT PK_tblCustomer PRIMARY KEY CLUSTERED (CustomerID)
    )
    GO

CREATE TABLE tblFilms (
    FilmID int,
    ...
    CONSTRAINT PK_tblFilms PRIMARY KEY CLUSTERED (FilmID),
    )
    GO

CREATE TABLE tblCinemaScreens (
    CinemaScreenID int, 
    ...
    CONSTRAINT PK_tblCinemaScreens PRIMARY KEY CLUSTERED (CinemaScreenID)
    )
    GO


CREATE TABLE tblCinemaScreenFilms (
    CinemaScreenFilmID int,
    CinemaScreenID int, 
    FilmID int
    CONSTRAINT PK_tblCinemaScreenFilms PRIMARY KEY CLUSTERED (CinemaScreenFilmID),
    CONSTRAINT FK_FilmID FOREIGN KEY (FilmID) REFERENCES tblFilms(FilmID),
    CONSTRAINT FK_CinemaScreenID FOREIGN KEY (FilmID) REFERENCES tblCinemaScreens(CinemaScreenID)
    )
    GO

CREATE TABLE tblBookings (
    BookingID int,
    CustomerID int,
    CinemaScreenFilmID int,
    ...
    CONSTRAINT PK_tblBookings PRIMARY KEY CLUSTERED (BookingID),
    CONSTRAINT FK_CustomerID FOREIGN KEY (CustomerID) REFERENCES tblCustomer(CustomerID),
    CONSTRAINT FK_CinemaScreenFilmID FOREIGN KEY (CinemaScreenFilmID) REFERENCES tblCinemaScreenFilms(CinemaScreenFilmID)
    )
    GO

Answer 5

您正在创建一个表 - tblFilms - 并在创建第二个表之前将外键添加到 tblCinemaScreens。

作为帮助，我通常会创建所有表，然后创建任何外键关系和其他约束。