It is a part of the OS of host computer and all physical inputoutput operations

It is a part of the os of host computer and all

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It is a part of the O.S. of host computer and all physical input/output operations are performed by it. It provides disk abstraction to file Manager s.t. file Manager need not be concerned with the physical characteristics of the underlying storage media. Functions of Data Manager : - Convert operations in users queries coming directly via query processor or indirectly in an application program from users logical view to a physical file system. - It interfaces with file system enforces constraints to maintain consistency. And integrity of the data as well as its security. (Authorization and Integrity Manager). - Synchronizing simultaneous operations performed by concurrent users. (Transaction Manager) - Back up and recovery operations (Transaction Manager) Q.100 Describe the GRANT function and explain, how it relates to security. What types of privileges may be granted? How are they revoked? (6) Ans : Since more than one user can access one database, there exists the need to restrict user from using entire database in any way. Setting up access privilege can do this. Any privilege can be granted to or revoked from user with taken of the GRANT and REVOKE statements. Each privilege can be granted or revoked individually or in a group. Such group of rights is called ROLE and rights can be granted or revoked into in the same way as to the user. Access privileges include SELECT, INSERT, UPDATE and DELETE. GRANT {statement|role_name} ON {object_name} TO {user|role_name_ 2 } [WITH GRANT OPTION] statement A statement to be granted or revoked. role_name The name of a role to be granted or revoked. object_name The name of an object (table, view or role) on which the rights will be changed. user The name of a user, the rights will be granted to or revoked from. All users are represented by the keyword PUBLIC.
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role_name_ 2 The name of a role, the rights will be granted to or revoked from. WITH GRANT Gives the administration right on object. OPTION right can grant rights, revoke rights, create role, change role and delete role. An example of granting permission to user B for reading EMP table is: GRANT SELECT ON emp to B; The REVOKE statement is used to revoke the permissions from the user. The syntax for REVOKE statement is given as: REVOKE {statement|role_name} FROM {user|role_name}; Q.101 Define the following terms (i) Catalog and meta data (ii) Parametric end users (iii) DBA (iv) Controlled redundancy (v) Snapshot (vi) Data sublanguage (vii) High level DML (viii) Data abstraction ( 16 ) Ans : i) Catalog and meta data A catalog is a compilation of records describing the contents of a particular collection or group of collections.Metadata (meta data, or sometimes metainformation) is "data about data", of any sort in any media. An item of metadata may describe an individual datum, or content item, or a collection of data including multiple content items and hierarchical levels, for example a database schema.
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