RELATIONAL MODEL
CONTENT
- Definition of Relational Model
- Creating and Modifying Relations using SQL
Definition of Relational Model
The relational model for database management is a database model that is based on first-order predicate logic, first formulated and proposed by E.F. Codd in 1969.
The purpose of the relational model is to provide a declarative method for specifying data and queries.
Creating and Modifying Relations using SQL
Creating and modifying relations simply is the process of creating and modifying a database. Data-definition queries can be very convenient. You can regularly delete and re-create parts of your database schema merely by running some queries. Consider using a data-definition query if you are familiar with SQL statements and you plan to delete and re-create particular tables, constraints, indexes or relationships.
A relation is a table structure definition (set of column definitions) along with the data appearing in that structure. The structure definition is the heading and the data appearing in it is the body, a set of rows. A database relvar (relation variable) is commonly known as a base table.
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