I'm not sure exactly where to post this but...

I have a client that is currently using Filemaker Pro as a database to store information about clients. It's strictly for offline use and will not be associated with a website. The client is unhappy with the software and feels they have outgrown it. They also report that the fact that it is not relational is problematic. Can anyone suggest an off the shelf product (affordable for a small sole-proprietor) that might meet my client's needs?

Sorry for the lack of detail. I am very new to databases and really don't know what's important when considering one.