Creating a scheduling website

I need a site to track and edit employee scheduling for a large number of employees. I need to have a main login page where you can login as either an employee or a scheduler. Each scheduler account will correspond to a separate schedule effecting one particular location, which will have multiple employee accounts. There will around 50 locations (with scheduler accounts) with around 100 employees per location. Scheduler will be an admin type login for a single location. The scheduler needs to be able to createdelete user accounts for each employee at that location, enter the days they are asked to work. Entry can be as simple as work on a whole day, minutes and hours are not relevant. The scheduler also needs to be able to view a monthly calendar and be able to click each date and see what employees are available for that day, and what are not. Scheduler should also be able to click on each employee and bring up a page showing their contact info. Locations should also be able to have more than scheduler. The employee login needs to be able to view the same calendar, but only showing the days they themselves are scheduled. The employee needs to be able to black out calendar dates that they are unavailable on, always whole days. This needs to correspond back the scheduler calendar so they can see who is unavailable on given days. Each employee needs an area where they can keep their contact info updated. (phone number, email, address) Employees accounts must also be able to be part of more than one location, but that must be setup by the scheduler. There must be three SuperAdmin type accounts that can createdelete the scheduler accounts, and customize location information. Customized location information would be name and phone number. I can give more details if needed, please email me. This is for a large company, obviously. But needs to be done as cheaply as possible. Time frame is not urgent. We do have hosting capability, but no database engines are available. I am open to suggestions, but would prefer to purchase a DB engine and setup on our own servers. It is easier, we could put each location as a subdomain, it might make the DBs less complex to create.