A database is a set of related data. A database management system (DBMS) allows users to access and perform operations on data in a database. Some key benefits of a DBMS include easy data use, centralized data control, and data security. Traditional file systems have disadvantages like data redundancy, inconsistency, and lack of integrity and security. There are different types of database models including hierarchical, network, relational, and object-oriented.

1. Data Resource Management
Module II

2. What is a database?
A set of related data is called database.
For example:
Student database that consists of the following fields, Enrollment
number, Student name, Department, Year, Address.
Employee database that consists of the following fields, Employee
number, Employee name, Department, Address, Date of joining,
Salary.

3. What is a Database Management
System?
DBMS is a software system that allows its users to access the data
contained in the database, in the form that they want.
DBMS acts as an interface between the user and the database. The user
requests the DBMS to perform various operations (insert, delete, update
and retrieval) on the database.
For example:
Salary Management System and
Ticket reservation system

4. Functions of DBMS

5. Benefits of a DBMS?
Easy to use – Adding, updating and deleting data in database
Centralized control of database – Share database to multiple user
Data Security – User based security to the database

6. Traditional File System:
Information typically stored using file-processing system
File processing is the process of creating, storing and accessing content of
files
Disadvantages of the file-processing system:
1. Data redundancy – Same data may appear in several files
2. Data inconsistency – Changes in data may not reflect in all files
3. Difficulty in data access
4. Data integrity – Database inaccurate and consistent
5. Data security – User level security

7. DBMS example
In a Telephone System Manufacturing company with more than 2,500
employees , if the Management needs a report like:
List of employees getting a salary of more than 10,000?

8. If it is a small company with 12 employees
SELECT * FROM Employee WHERE salary > 10,000
The above oracle or SQL command lists all records which have a
salary more than 10,000

9. Types of DBMS

10. Types of Databases
Hierarchical database
Network database
Relational database
Object-oriented database

11. HIERARCHICAL DATABASE
A DBMS is said to be hierarchical if the relationships
among data in the database are established in such a
way that one data item is present as the subordinate of
another one.
Here subordinate means that items have 'parent-child'
relationships among them.

12. NETWORK DATABASE
 A DBMS is said to be a Network DBMS if the relationships
among data in the database are of type many-to-many.
 The structure of a network database is extremely complicated
because of these many-to-many relationships in which one record
can be used as a key of the entire database.

13. RELATIONAL DATABASE
 A relational database is a database that stores information
about both the data and how it is related.
 "In relational structuring, all data and relationships are
represented in flat, two-dimensional table called a relation."
 A number of RDBMSs are available, some popular examples are
Oracle, Sybase, Ingress,Informix, Microsoft SQL Server,
and Microsoft Access.

14. OBJECT-ORIENTED DATABASE
 Object-oriented databases use small, reusable chunks of software
called objects.
 Each object consists of two elements:
1) a piece of data (e.g., sound, video, text, or graphics), and
2) the instructions, or software programs called methods, for what
to do with the data.