ENTITY In DBMS

 ENTITY 

An entity is a object which differenciate from another object in the real world.

For eg:  employee,customer,doctor,patient all those are entity.

Entity is a set of attribute.Attribute is a field which describe the description property of entity.

A set of some type of entity is called  entity set.



ROLE OF DBMS

One of the main reason for having DBMS is to have control of both data and program execessing that data.The DBMS as a person or program having such control over thr system.

The main role of DBA:

1.Schema defination

The creation of the original database schema by writting a set of defination which are translated by the DDL compilar(Data Defination Language) to a set of table that are permanently stored in the data dictonary.

2.Storage Structure and access method defination. The creation of appropriate and excess method by writting a set of definitions which are translated by the data storage and defination language compiler.

3.Schema and Physical organisation modification.Either of modification of database schema or the description of the physical organisation. These change are perform by writting a set of defination which are used by DDL compiler or the data storage and defination language compiler to generate modification to the appropriate internal systems (data dictionary).

Granting of Autorization for data Access:

The granting of different types of autorisation for data access to the various user of the database. Integrity constraint are kept in a special system i.e. consulted by the database manager and DBA user to carry out data administration in data dictonary.

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