best relationship for this design? There is a table users with autoincrement primary key id.

There is also a table employees (every employee is a user but not vice versa). The employees primary key is userid. The field userid is not autoincrement.

employees.userid should be a foreign key for users.id.

Which kind of relationship in Workbench it should be?

As far as I understand:


It cannot be 1:1 relationships because for a given user the corresponding employee may not exist.
It is not advisable to be 1:n relationship because n can be only 0 or 1.
It should be an identifying relation because a user is determined by an employee.


Please advise me what is the best relationship in this case.
I think it would be best that you learned about relationship types without using an IDE.

If every employee is a user, then it should be a straight 1:1 relationship.

If every employee is not a user, then you should not be using userid as the primary key. Rather, create a surrogate primary key for the employee and make userid a nullable foreign key.