Bandwidth managment for the internet connection

[voltron81]

Hello to everybody.
Do you have any suggestion how to realize a Bandwidth managment on a debian system?
I'll create a GUI where somebody can decide who will have priority for the internet connection, based on the field 'user' on a mysql database.

So I need a program (not GUI) that will allow me to fetch some data from a database and will split the bandwidth with different priorities...
Let's say for example:
User1 will use the 50% of the bandwidth (upload and download)
User2 will use the 30% of the bandwidth (upload and download)
User3 will use the 20% of the bandwidth (upload and download)

Any idea how to realize it?