Database systems can be based on different data models or database models respectively. A data model is a collection of concepts
and rules for the description of the structure of the database. Structure of the database means the data types, the constraints
and the relationships for the description or storage of data respectively.
The most often used data models are:
|Network Model and Hierarchical Model||The network model and the hierarchical model are the predecessors of the relational model. They build upon individual data sets and are able to express hierarchical or network like structures of the real world.|
|Relational Model||The relational model is the best known and in today’s DBMS most often implemented database model. It defines a database as
a collection of tables (relations) which contain all data.
This module deals predominantly with the relational database model and the database systems based on it.
|Object-oriented Model||Object-oriented models define a database as a collection of objects with features and methods. A detailed discussion of object-oriented databases follows in an advanced module.|
|Object-relational Model||Object-oriented models are very powerful but also quite complex. With the relatively new object-relational database model is the wide spread and simple relational database model extended by some basic object-oriented concepts. These allow us to work with the widely know relational database model but also have some advantages of the object-oriented model without its complexity.|