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Record based Logical Models: Use records as the key data representation components
Examples:
Relational Model: It shows data as well as relationship between data in the form of tables.
Constraints are stored in a meta-data table. This is a very easy model and is based on a proven mathematical theory. This is the most usually used data base model.
Network Model: In this model data is shown as records and relationship as links. A easy network model example is explained in Figure . It shows a sample diagram for such a system. This model is a very good quality model as far as conceptual framework is concerned but is today not used in database management systems.
Whst is logical schema ? Logical schema is the entire database.
Update Operations and Dealing with Constraint Violations There are three basic operations to be executes on relations: Insertion Deletion Update The INSER
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