Question

I have two tables in my SQL database:

Company:

• ID (autoincrement)
• name
• address
• …

Employees:

• ID (autoincrement)
• Company_id
• internal_id
• name
• lastname

The problem is that I would like to have a employee id (internal_id) that is relative to the company they belong to. I got this dilema since I’m really been searching what would be the cleanest way to implement it.

One option would be to just make a kind of SELECT MAX(internal_id) FROM employees WHERE company_id = X, but the problem would be that if I happen to delete the last employee the next one would be created with the ID of the next.

Any ideas or suggestions?

PD: The reason of why I want to do this is that i dont want a user from company X create an employee that is for example ID=2000, while the last employee created in his company was, say, 1532. this would normally happen in a system in wich Company Y and Z also create employees on the same system. I want this ID not to use as a foreign_key, but to have it for internal (even documents or reports) use.

PD2: In this case the employees will never have to change companies

Answer 1

There are lots of questions here about creating ‘Business’ IDs or numbers that are unrelated to the primary keys.

In your case I would create a column on the Company table ‘NextEmployeeID’ Then when creating a new employee simply retrieve the value and increment it.

Now I leave it up to you to figure out what happens if the employee changes companies. 🙂