If you are approaching this as a learning project I do not yet have th
+e skills to advise you. 
But if you wish a quick ready made answer using MySQL try
 
http://www.artronic.hr/mysql/index.htm

 for a MySQL database that does exactly what you describe

-_-_-_-_-_-_-_-_-_-_-_-
My memory concerns me
- but I forget why !!!
[download]