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2. Data Consistency: A DBMS provides data consistency to a larger extent as the changes
made at one place are reflected at all other places or to all the users.

3. Sharing of Data: By using a DBMS, not only can existing applications share data in the
database, but new applications can also be developed to operate against the same stored
data.
4. Reduced Programming Effort: A DBMS saves a lot of programming effort since a user
need not write programs for query processing involving several tables or files, report
generation, addition, modification and deletion of data, etc. Thus, it provides easy
retrieval of data.
5. Database Enforces Standards: With centralized control of the database, the DBA
(Database Administrator) can ensure that all applicable standards are followed in the
representation of data, i.e., format, documentation standards and conventions, etc.

6. Improved Data Integrity: Data integrity refers to the validity and consistency of stored
data. For example, the system itself checks for the correct information to be entered by
the user in the correct format. It consists of various constraints.
7. Privacy and Security: Data security refers to protection of data against accidental or
intentional disclosure to unauthorized persons. Since there is centralized control, the
data is protected.

8. Economical: Combining all the organization’s operational data into one database and
creating a set of applications that work on this single source of data can result in cost
savings. The overall maintenance cost of data is reduced.
9. Improved Backup and Recovery System: A database system provides facilities for
recovery from hardware or software failures.

10. Meeting Enterprise Requirements than Individual Requirements: Since many types
of users with varying levels of technical knowledge use a database, a DBMS should
provide a variety of user interfaces.

CTM: The repetition (duplication) of same data at multiple places in a database is known as data
redundancy.

12.3 DBMS MODELS

Data models define how the logical structure of a database is modelled. A data model is an integrated
collection of conceptual tools that can be used to describe the structure of the database along with
the appropriate data types, relationships and constraints required to be applied on the data.

Data Models are used to implement abstraction in a DBMS. They are a communication tool. Data
Relational Database and SQL
models define how data is connected and how it is processed and stored inside the system. They
organize data for various users. A data model should be able to give best data representation and
should possess the following desirable characteristics:
(a) Data models should be presented graphically using diagrams and symbols.

(b) Data representation in a data model should have no data redundancy.
(c) A data model should be made available and shared by various applications.

(d) Data represented should be consistent, stable and valid in all aspects.
12.5