引用表中没有与外键中的列列表匹配的主键或候选键

Question

我试图创建一些基本的SQL表，但我不断收到以下错误：

引用表'CART'中没有主键或候选键与外键'FK__ORDERS__CART_ID__2B3F6F97'中的引用列列表匹配

这是我正在使用的当前代码。

create table USERS
(
    User_ID int NOT NULL primary key,
    Address varchar(30) NOT NULL,
    Email varchar(30) NOT NULL,
    Password varchar(30) NOT NULL,
    Phone varchar(30) NOT NULL,
    F_Name varchar(30) NOT NULL,
    L_Name varchar(30) NOT NULL,
    Date_of_Birth varchar(30) NOT NULL
)

create table PAYMENT
(
    User_ID int NOT NULL primary key,
    Credit_Card varchar(30) NOT NULL,
    Debit_Card varchar(30) NOT NULL,
    Google_Pay varchar(30) NOT NULL,
    Apple_Pay varchar(30) NOT NULL,
    Paypal varchar(30) NOT NULL,
    foreign key (User_ID)
    references USERS(User_ID)
)

create table CART
(
    User_ID int NOT NULL,
    Cart_ID int NOT NULL,
    Total_Price float NOT NULL,
    primary key (Cart_ID, User_ID),
    foreign key(User_ID)
    references USERS(User_ID)
)

create table ORDERS
(
    Order_ID int NOT NULL primary key,
    Total_Price float NOT NULL,
    Payment_Method varchar(30) NOT NULL,
    User_ID int NOT NULL,
    CART_ID int NOT NULL,
    foreign key (User_ID)
    references USERS(User_ID),
    foreign key (Cart_ID)
    references CART(Cart_ID),
)

create table ORDER_HISTORY
(
    User_ID int NOT NULL,
    Order_ID int NOT NULL,
    primary key (User_ID, Order_ID),
    foreign key (User_ID)
    references USERS(User_ID),
    foreign key (Order_ID)
    references ORDERS(Order_ID)
)

我试过修改东西并移动它们但是不能让错误消失。我怀疑这可能非常简单明了，但由于我对SQL很新，我可能会错过它。

Answer 1

由于表CART具有复合主键，因此您应该引用复合主键：

 create table ORDERS
(
    Order_ID int NOT NULL primary key,
    Total_Price float NOT NULL,
    Payment_Method varchar(30) NOT NULL,
    User_ID int NOT NULL,
    CART_ID int NOT NULL,
    foreign key (User_ID)
    references USERS(User_ID),
    foreign key (Cart_ID, User_ID)
    references CART(Cart_ID, User_ID),
)

Answer 2

cart有一个复合主键(cart_id, order_id)。这些列中的每一列都不是独立的主键，只是它们的组合。来自orders的外键应该是相同的 - 你应该有一个基于两者组合的外键：

create table ORDERS
(
    Order_ID int NOT NULL primary key,
    Total_Price float NOT NULL,
    Payment_Method varchar(30) NOT NULL,
    User_ID int NOT NULL,
    CART_ID int NOT NULL,
    foreign key (User_ID)
    references USERS(User_ID),
    foreign key (Cart_ID, User_id) -- here
    references CART(Cart_ID, User_id),
)

Answer 3

在表Cart中，您需要使用PRIMARY KEY定义Cart_ID。如果由于某种原因您不能或不想定义PRIMARY KEY，则在同一列上尝试UNIQUE KEY约束。

Answer 4

它是Cart表上的主键。

CREATE TABLE [dbo].[CART](
    [User_ID] [int] NOT NULL,
    [Cart_ID] [int] NOT NULL,
    [Total_Price] [float] NOT NULL,
 CONSTRAINT [PK__CART__D6AB58B9B18E85A5] PRIMARY KEY CLUSTERED 
(
    [User_ID] ASC,
    [Cart_ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[CART]  WITH CHECK ADD FOREIGN KEY([User_ID])
REFERENCES [dbo].[USERS] ([User_ID])