SQL Server表创建错误：引用中没有主键或候选键

Question

A very basic script is driving me crazy. It says it cant find a referenced key. Not idea what it's all about. I'm am using SQL SERVER 2014 and this script is for the creation of my database tables. I'm trying to make the id_TABLE_1 in the table TABLE_2 reference the id of the table TABLE_1 .

CREATE TABLE TABLE_1
(
    id int identity,
    email varchar(50) not null,

    constraint PK_TABLE_1 primary key (id,email)
)
GO

CREATE TABLE TABLE_2
(
    id int identity,
    id_TABLE_1 int not null,

    constraint PK_TABLE_2 primary key (id),
    constraint FK_TABLE_2 foreign key (id_TABLE_1) 
        references TABLE_1(id) on delete cascade
)
GO

The error is :

Msg 1776, Level 16, State 0, Line 32
There are no primary or candidate keys in the referenced table 'TABLE_1' that match the referencing column list in the foreign key 'FK_TABLE_2'.

Msg 1750, Level 16, State 0, Line 32
Could not create constraint or index. See previous errors.

Can you help me here ?

Answer 1

As per comment, you are trying to reference an index that doesn't exist. The primary key on your TABLE_1 table is a composite key containing two columns: id and email .

For this to compile, you can either alter your primary key to:

CONSTRAINT PK_TABLE_1 PRIMARY KEY (id)

or create a new index on just the id column:

CREATE INDEX IX_TABLE_1_id ON TABLE_1 (id);

Answer 2

It doesn't make sense to have a composite primary key that includes an identity column. The id column is already unique and non-NULL, so it should be the primary key.

If you want the email to be unique as well then remove it from the primary key and declare it as unique.