We can create a database ER diagram that fits your internal needs. Once approved, we can create it in Oracle, Sybase, MySql, or Postgre SQL.
As a recent example, a client wanted to build an app for EHR (Electronic Health Records). After spending some time finding out what sort of objects and relationships he had in mind, we were able to construct an ER diagram (Entity-Relationship). And we implemented it for him in MySQL and then he was start creating his application while accessing the database!