Need query for limited selection

[Anon]

I am making a web site for a company that lists a range of projects and a range of employees. I have made an admin page where I link these together, so that you can see what employees have been working on the different projects.

It is set up like this: I get a list of the projects I can choose to link to. After choosing the relevant project I get a list of the employees. After linking this employee I get a list of the employees again, in case I want to add more. However, the employee I just added is still shown. How can I just show the employees that are left?

I have one table with the projects, one with the employees, and one with a combination of the project_id and employee_id.

It'd be great with some help, if anyone even understands what I'm asking about.

[Anon]

Select employee_id
from employees
where employee_id not in (select employee_id
from link_table);