The employee and project many-to-many is exactly my concern. Just to make sure I understand correctly, did you mean to type "not a proper one-to-many relationship"? I wasn't sure if it was a typo or if there is ever a proper m-to-m. I'm pretty sure that's what you meant, regardless, I'll start a junction table!
Originally Posted by r937
what happens if more than one employee is on a single project?
what you have is not a proper many-to-many relationship
I believe r937 did mean Many-To-Many. I believe his point was that a project will typically have more than one person working on a project. And, I think the assumption was, one employee will work on more than one project at a time.
So you really should have a third table (ProjectTeam???) that stores the people that are working on the project. However, your schema may work for you if your business requires you to only have one Project Leader. If, for some reason, there is a very large project and for this ONE project there are two leads, your database won't be able to handle it.