I have never done any serious SQL design before. Anyways I have to store a hierarchical data structure, similar to a tree in a SQL database.<BR><BR>Right now I simply add a "parent_id" column in ...

The way data is actually stored in a database and managed by a DBMS is defined by a database model. Essentially, there are three types of database models: Relational, Hierarchical and Network.

A hierarchical database management system allows data to be stored in such a way that one data item is a subunit of other data. The system is ideal for storing data that has attributes and features.