Question

.1. Discuss the advantages and disadvantages of Database Management Systems (DBMS). 

2. What is a data model? Discuss the main types of data models. 

3. Define the term "database integrity." How does database integrity differ from database security?

Answer 1

1)

Advantages of DBMS

• DBMS offers a variety of techniques to store & retrieve data
• DBMS serves as an efficient handler to balance the needs of multiple applications using the same data
• Uniform administration procedures for data
• Application programmers never exposed to details of data representation and storage.
• A DBMS uses various powerful functions to store and retrieve data efficiently.
• Offers Data Integrity and Security
• The DBMS implies integrity constraints to get a high level of protection against prohibited access to data.
• A DBMS schedules concurrent access to the data in such a manner that only one user can access the same data at a time
• Reduced Application Development Time

Disadvantage of DBMS

DBMS may offer plenty of advantages but, it has certain flaws-

• Cost of Hardware and Software of a DBMS is quite high which increases the budget of your organization.
• Most database management systems are often complex systems, so the training for users to use the DBMS is required.
• In some organizations, all data is integrated into a single database which can be damaged because of electric failure or database is corrupted on the storage media
• Use of the same program at a time by many users sometimes lead to the loss of some data.
• DBMS can't perform sophisticated calculations

2)

Data Model can be defined as an integrated collection of concepts for describing and manipulating data, relationships between data, and constraints on the data in an organization.

They fall into three broad categories:

• Object Based Data Models
• Physical Data Models
• Record Based Data Models

Object Based Data Models

Object based data models use concepts such as entities, attributes, and relationships. An entity is a distinct object (a person, place, concept, and event) in the organization that is to be represented in the database. An attribute is a property that describes some aspect of the object that we wish to record, and a relationship is an association between entities.

Physical Data Models

Physical data models describe how data is stored in the computer, representing information such as record structures, record ordering, and access paths. There are not as many physical data models as logical data models, the most common one being the Unifying Model.

Record Based Logical Models

Record based logical models are used in describing data at the logical and view levels. In contrast to object based data models, they are used to specify the overall logical structure of the database and to provide a higher-level description of the implementation. Record based models are so named because the database is structured in fixed format records of several types. Each record type defines a fixed number of fields, or attributes, and each field is usually of a fixed length.

Answer 2

Difficult Backup And Recovery

Database is processed and handled by several users concurrently, so it becomes very difficult to get the exact state of database at the time of failure. It creates many problems and users get confused about what to do next.

So, it is very difficult to take backup and recover the database as just one application program may pose serious problems.