SQL Add foreign key to existing column

Question

If I am using the following SQL command in SQL Server 2008 to update a table with a foreign key constraint: ``` ALTER TABLE Employees ADD FOREIGN KEY (UserID) REFERENCES ActiveDirectories(id) ``` `UserID` being my FK column in the `Employees` table. I'm trying to reference the `UserID` in my `ActiveDirectories` table. I receive this error: Foreign key 'UserID' references invalid column 'UserID' in referencing table 'Employees'.

Accepted Answer

Error indicates that there is no UserID column in your Employees table. Try adding the column first and then re-run the statement.

```
ALTER TABLE Employees
ADD CONSTRAINT FK_ActiveDirectories_UserID FOREIGN KEY (UserID)
    REFERENCES ActiveDirectories(id);
```

SQL Add foreign key to existing column

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