SMU MBA ASSIGNMENTS

Answer : A database model is a theory or specification describing how a database is structured and used. Several such models like Hierarchical model, Network model, Relational model etc., have been suggested.

Data Model, Schemas and Instances:

Data Model  :

It is a set of Concepts for viewing a set of data in a structured way. This can be easily understood by professionals and non-technical users. It can explain the way in which the organization uses and manages the information.

Concepts used in data Model

Entity An entity is something that has a distinct, separate existence, though it need not beef a material existence.E.g. – Employee.

Attribute

It is the property that describes an entity

It is a characteristic or property of an object, such as weight, size, or colour Relationship

Describes the relationship between two or more entities

 

Schemas

The description of the data base means defining the names, data type, size of column in a table and database [actual data in the table] itself.

The description of a database is called the database schema [or the Meta data].

Description of a database is specified during database design and is not frequently changed.

Roll No.

Name Semester

Branch

 

Instances

The collection of data stored in the database at a particular moment is a database instance or database state or snapshot.

These changes very frequently due to addition, deletion and modification.

Roll No.

Name Semester

Branch

1

Rajesh Parch

Ii

E & C

Data independence is defined as the ability to modify a schema definition in one level without affecting schema definition in a higher level.

 

Physical data independence

This is the ability to modify the physical scheme without causing application programs to be rewritten. Modifications at this level are usually to improve performance.

Logical data independence

This is the ability to modify the conceptual scheme without causing application programs to be rewritten. This is usually done when theological structure of database is altered. Logical data independence is harder to achieve, as the application programs are usually heavily dependent on the logical structure of the data. An analogy is made to abstract data types in programming languages.

Q2. What is a Biters? Describe the structure of both internal and leaf nodes of a Biter?

 

Q3. Describe Projection operation, Set theoretic operation & join operation?

Q4. Discuss Multi Table Queries?

 

Q5. Discuss Transaction Processing Concept? 10.2 Describe properties of Transactions?

 

Q6. Describe the advantage of Distributed database? What is Client/server Model? Discuss briefly the security and Internet violation?

irect access to the data.