7. Explain Network and Relational data models.
Explain Network and Relational data models
The network model is a database model conceived
as a flexible way of representing objects and their relationships. Its
distinguishing feature is that the schema, viewed as a graph in which object
types are nodes and relationship types are arcs, is not restricted to being a
hierarchy or lattice.
The relational model for database management is
a database model based on first-order predicate logic, first formulated and proposed
in 1969.
In the relational model of a database, all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a relational database.
In the relational model of a database, all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a relational database.
In the relational model, related records are
linked together with a "key".
The purpose of the relational model is to provide a declarative method for specifying data and queries: users directly state what information the database contains and what information they want from it, and let the database management system software take care of describing data structures for storing the data and retrieval procedures for answering queries.
The purpose of the relational model is to provide a declarative method for specifying data and queries: users directly state what information the database contains and what information they want from it, and let the database management system software take care of describing data structures for storing the data and retrieval procedures for answering queries.
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