On Transact SQL language the Msg 1776 Level 16 - There are no primary or candidate keys in the referenced table means that the primary key is missing.
Msg 1776 Level 16 Example:
Invalid alter:
USE tempdb;
GO
ALTER TABLE dbo.EMPLOYEES
ADD CONSTRAINT FK_ID_DEP FOREIGN KEY (DEPT_ID)
REFERENCES dbo.departments (ID);
GO
| Message |
|---|
| Msg 1776, Level 16, State 0, Line 3 |
| There are no primary or candidate keys in the referenced table 'dbo.departments' that match the referencing column list in the foreign key 'FK_ID_DEP'. |
| Msg 1750, Level 16, State 1, Line 3 |
| Could not create constraint or index. See previous errors. |
Correct alter:
USE tempdb;
GO
ALTER TABLE dbo.departments
ADD CONSTRAINT PK_DEPT_ID PRIMARY KEY CLUSTERED (ID);
GO
ALTER TABLE dbo.EMPLOYEES
ADD CONSTRAINT FK_ID_DEP FOREIGN KEY (DEPT_ID)
REFERENCES dbo.departments (ID);
GO
| Message |
|---|
| Command(s) completed successfully. |
Other error messages:
- The CREATE UNIQUE INDEX statement terminated because a duplicate key was found for the object name
- Could not create constraint or index
- Table already has a primary key defined on it
- Column name does not exist in the target table or view
- Violation of PRIMARY KEY constraint
- Column names in each table must be unique
- There is already an object named in the database