This document discusses key concepts related to databases and database management systems (DBMS). It defines metadata as data about data, such as information about a database's structure, that is stored in the data dictionary. It describes problems with traditional two-file processing systems and how the database approach integrates data and reduces data duplication. The core functions of a DBMS are presented, including its role in translating requests between users and the database. Advantages and common applications of DBMS are outlined.

1. Er. Nawaraj Bhandari
Topic 2:
Databases and Database Management Systems

2. Metadata
 Metadata is data about data.
 It is the way in which the database keeps information about its own
structure.
 Metadata is stored in the data dictionary.

3. Metadata
Name Type Length Description
Student Name Character 50 Student’s
name
Student ID Number 8 Unique identification
number for a student
Date of Birth Date 8 Student’s date of birth
in the format
’01.01.80’

4. Metadata in MS Access

5. Metadata in Oracle SQL
SQL> DESC emp
Name Null? Type
------------------------------- -------- ----
EMPNO NOT NULL NUMBER(4)
ENAME VARCHAR2(10)
JOB VARCHAR2(9)
MGR NUMBER(4)
HIREDATE DATE
SAL NUMBER(7,2)
COMM NUMBER(7,2)
DEPTNO NUMBER(2)
SQL>

6. Metadata(Data Dictionary)
Datatypes
1. VARCHAR
2. TEXT
3. INTEGER
4. DECIMAL
5. DATE
Column Name Type Length Null Key Constraint

7. Activity
 Define metadata for data about the following:
Students in a college database
College Examination
Books in a library system
Holidays booked by a person at a workplace
Shopping Mart
 Try to think about what data needs to be kept - will it be a character,
date or number?

8. Two-File Processing System
Customer
File
User
Customer
Processing System
Rental
Processing System
Customer File
Rental File
Rental File
User

9. Two-File Processing System
 The example used is of a car rental system.
 One system processes CUSTOMER data, and the other processes
RENTAL data.
 Each of the files and the applications that use them are totally
separate.
 Although this is an improvement over older manual systems, there are
a number of problems.

10. Problems in Two-File Processing System
1. Data are separated and isolated.
2. Data are often duplicated.
3. Problem of Data integrity(meaning of data)
4. Application programs are dependent on file formats.
5. Problem of Data Security.
6. It is difficult to represent data in a user’s perspective.

11. Basic Structure of a Database
Customer
Processing
Application
Rental
Processing
Application
Other
Application
DBMS
User
User
User
Database

12. Database System in Detail
DATA
Customer
Processing
Application
Rental
Processing
Application
Other
Application Database
DBMS
User
User
User
METADATA
Database
Management
System
Application Requests
Data
Data
Data
Application Requests
Application Requests
DBMS serves as intermediary
between user and the database by translating
user requests into the complex code required
to fulfill those requests.
Application programs might be written in a programming
Language, such as Visual Basic or C++, or it might
be created through a DBMS utility e.g. Access’s forms wizard.

13. DBMS
 DBMS serves as intermediary between user and the database by
translating user requests into the complex code required to fulfill
those requests.
 DBMS stands for data base management system. This is a software
system which facilitates the formation, maintenance as well as use of
an electronic database. It permits organizations to suitably develop
databases for a range of applications by database administrators and
certain specialists.

14. Features of the Database Approach
1. Integrated data
2. Reduced data duplication
3. Program/data independence
4. Easier representation of users’ perspectives

15. Common Applications
1. Forms
2. Reports
3. Web-applications
4. Desktop Applications

16. DBMS Functions
1. CRUD functions
2. Data dictionary
3. Transaction management
4. Concurrency control
5. Recovery
6. Authorization
7. Data integrity
8. Administration utilities

17. Advantages of DBMS
 Control of data redundancy
 Improved data integrity or Data consistency
 Sharing of data
 Improved security
 Enforcement of standards
 Improved data accessibility and responsiveness
 Improved maintenance
 Increased concurrency
 Improved backup and recovery services

18. Disadvantages of DBMS
 Complexity
 Size
 Cost of DBMSs
 Additional hardware costs
 Cost of conversion
 Performance
 Requires skilled manpower

19. DBMS – Architecture
• The DBMS is the software that handles all the interactions between
applications and the database.
• Paul Benyon-Davis provides a useful way of looking at the structure of
the DBMS itself i.e. DBMS Architecture.
• 3 layers
1. Kernel
2. Interface
3. Toolkit

20. Kernel, Interface and Toolkit
DBMS Toolkit
Interface
DBMS Kernel
Database

21. Kernel, Interface and Toolkit
1. Kernel
 Central engine, which operates most of the core data management
functions
2. Toolkit
 The tools and applications that interact with the end-users.
 These might be provided as part of the DBMS product or as separate
piece of software.
Eg. Batch Processing of supply chain, Processing sales.
3. Interface
 It handles the interaction between the toolkit and the kernel
Eg. design of screens for applications such as point of sale

22. References
 http://www.ask.com/question/what-is-a-dbms
 http://en.wikipedia.org/wiki/Microsoft_SQL_Server

23. Data Models
 Hierarchical
 Network
 Relational
 Object-oriented
 Deductive
 Post-relational

24. ANY QUESTIONS?