Dbms Assignment 1

DBMS ASSIGNMENT-1
NAME: D.RAJEEV KUMAR

ROLL.NO:23B81A6637
CLASS:CSM-A
1)a)State the purpose of database management system?
• Data Independence
• Efficient Data Access
• Data Integrity and security
• Data Administration
• Concurrent Access and crash Recovery
• Reduced Application Development Time
1b)Describe the levels of abstraction?

DATA ABSTRACTION:
Levels of Abstraction form DBMS:
Data abstraction is the procedure of concealing relevant
or unwanted data from the end user. The main task of Data
base system is to provide the abstract view of the data.
Physical or Internal level:
• It is the lowest level of data abstraction in the database
management system.
• If defines How data is Stored actually stored in the database.
• It defines methods to access the data in the database
• Database Developers will involve not even in the database
Logical or conceptual level:
• It is the intermediate or next level of data abstraction.
• It explains WHAT data is to be stored in database, and what
the relationship in between them
• It describes the structure of the entire data in the tom et
tables.
• It is less complex than the physical level.
• Data base administrator will involve in this level.
View or External level:
• It is the highest level of data abstraction
• There are different views at this level that define the parts of the
overall data of the database.
• This level is for the end-user interaction.
• At this level, end users can access the data based on their queries.
2a)Explain the three level architecture of database system ? How is
data independence achived in this system?
The architecture of database system is greatly influenced by the
computer system on its work .the functional component of a
database system can be divided in to
Query processer: It helps the database system to simplify and
facilitate the access of the data.
The components include: DDL Interpreter,DML Complier,Query
evaluation engine.
Storage manager:-Storage manager is a program module that provides
the interface between the low-level data stored in the database and
the application programs and queries submitted to the system.The
storage manager is responsible to the following tasks:
• Interaction with the file manager
• Efficient storing, retrieving and updating of data
Disk manager: the responsibility of a disc manager is to store the data
in different structures and to organise them efficiently.
Data Independence:-
The ability to modify the schema in one level without affecting the
schema is next higher level is called Data Independence.
These Data Independence is in two types.
• Logical Data Independence:- The ability to modify the Logical Schema
without affecting the schema in next higher level .
• Physical Data Independence:- The ability to modify the Physical
Schema without changing the Logical schema.
2b)Explain about different types of data models with example?
Data Models:
There are 4 types of data models in DBMS. They are:-
Relational Model:
The Relational model uses a collection of tables to represent both data and
relationships. Each Table bas multiple columns and each column has a unique name.
Tables are also known as Relations. The columns in the table are attributes.
Entity-Relationship model:
An entity is a thing on object in the real world that is distinguishable from
other objects. The entity relationship model is based on a collection of basic objects
called entities and the relationship among these objects.
Object Oriented Model:
It is based on object oriented programming language paradigm. Inheritance,
object identity and encapsulations. It can be seen as extending the E-R model with
opps concepts.
Semi Structured data models:
Semi structured data models permit the specification of data, where individual
data items of same type may have different set of attributes. XML language is widely
used to represent Semi structured data.
ex:- E-mail
3)A)List various categories of database users and discuss their interfaces to DBMS?
Users are differentiated by the way they expect to interact with the system.
Application programmers: interact with system through DML calls.
Specialized users: write specialized database applications that do not fit into the traditional data
processing framework
Sophisticated users: form requests in a database query language.
Naive users: invoke one of the permanent application programs that have been written previously
3b)Explain the responsibilities of database administrator?

DATABASE ADMINISTRATOR:
Coordinates all the activities of the database. System; the database administrator has a good
understanding of the enterprise's information resources and needs.
Database administrator's duties include:
Schema definition
Storage structure and access method definition
Schema and physical organisation modification.
Granting user authority to access the database
Specifying integrity constraints-
Acting as connection with users.
Monitoring performance and responding to changes in requirements.
4)Draw and explain all elements of E-R Diagrams?
4(b): ER Diagram for a Company
The company needs to store information about:
Employees (Attributes: SSN, salary, phone_no)
Departments (Attributes: dept_no, dept_name, budget)
Employees' Children (Attributes: name, age)
Employees work in departments.
Each department is managed by an employee.Design E-R digram and construct database
thar captures this information.
5)A)Design how translating ER diagrams with relations with key constrating with
participation constraints and aggregation possible using the entities employee
(ssn,name,lot),projects(pld,started-on,pbudget)department(did,dname,budget)for
relationship sets monitors and sponsors.
6)Define following:
I. Instance: Actual content of database at a particular moment of time in database.
II. Schema: The overall structure of a database is called schema.
III. Refecential integrity constraint (foregin key): It is used to link two tables .
IV. Super key: It is a set of one or more attributes of a table which is uniquely identified.
V. Candiate key: It is a subset of attributes that are uniquely identified in a table.
VI. Primary key: unique value in a table with out any repeation is called Primary key.
B)Demonstrate usage of DML,DDL,DCL with suitable example
DML(data manuplation language):
Insertion,update,delete
Eg: insert into student values(‘101’, ‘dbms’,18);
delete from student where stdname=‘dbms’;
DDL(data definition language):
Create,alter,drop,truncate
Eg: truncate table student;
Drop table student;
DCL(data control language):
Grant ,revoke
Grant DBA to student;

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DBMS ASSIGNMENT-1

NAME: D.RAJEEV KUMAR

1b)Describe the levels of abstraction?

3b)Explain the responsibilities of database administrator?

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