 |
 |
 |
|
 |
|
 |
|
|
 |
 |
 |
Summary
In this lesson, the most often used database models (relational, object oriented and object relational) and the database technologies
based on them were discussed. Such a database model offers some basic rules how a conceptual schema can be transfered in a
specific database environment and described by means of a logical scheme. The data description is the base for the following
creation and management of the database instances with the actual data. Logical modelling on the base of a relational data
model will be discussed in the later lesson Logical Modelling.
Following the generic database architecture based on the 3-scheme-architecture was discussed. This 3-scheme-architecture extends
the logical scheme with an internal and an external scheme. The concept of dividing it into three parts is an important prerequisite
for the earlier mentioned data independence and the realisation of interfaces for the communication between applications and
the database management system. Most of the known database systems offer an interface on the bases of the structured query
language SQL. The basic elements and the use of SQL will be discussed in the later lesson Structured Query Language SQL.
 |
|
|
|
|
|
|
|
