I'm writing a database application, and I want to use a tree to display the information.

Say there are three fields (a,b,c) for each entry in the database. Each 'a' can have more than one 'b', and each 'b' can have more than one 'c'. Here's how it's suposed to look
-root
   a1
      b1
         c1
         c2
      b2
         c3
   a2
     b3
        c4

My question is this: How would I go about creating a model using a list of topics? I have created Data containers for the information from the database, each linking to a parent, so an entry of 'c' links to it's parent 'b', and so on, but I could not figure out how to check if the model already contained a specific child node...