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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.
Relations create the database. They must satisfy various properties, like no duplicate tuples, no ordering of tuples, and atomic attributes, etc. Relations that satisfy these basic
Differentiate between a Global and a Local temporary table? - A local temporary table exists only for the duration of a connection or if defined inside a compound statement, fo
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An ideal data dictionary should have everything a DBA wants to know about the database. 1 Conceptual, External, and internal database descriptions. 2. Descriptions of attr
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Physical Records These are the records that are stored in the secondary storage devices. For the database relation, physical records are the group of fields kept in adjacent me
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