Advantages And Disadvantages Of Database Management System

Overview of DBMS
Database is collection of data which is related by some aspect. Data is collection of facts and figures which can be processed to produce information. Name of a student, age, class and her subjects can be counted as data for recording purposes.
Mostly data represents recordable facts. Data aids in producing information which is based on facts. For example, if we have data about marks obtained by all students, we can then conclude about toppers and average marks etc.
A database management system stores data, in such a way which is easier to retrieve, manipulate and helps to produce information.

Content
Overview of DBMS 2
Content 3
1.0 Evolution of Database Management System 4
1.1 Before 1950’s 4
1.2 1950’s and early

File Based System Approach 7
2.1 Database Management System Approach 7
2.2 File Based System Approach 7
2.3 Disadvantages of File Based System Approach 8
2.4 Advantages of the Database System Approach 9
3.0 Job Roles related to Database Management Systems 11
3.1 Data Administrator (DA) 11
3.2 Database Administrator (DBA) 12
3.3 Database Designer 13
3.4 Application Developer 13
3.5 End Users 13 1.0 Evolution of Database Management System
1.1 Before 1950’s
• Before 1950’s data was stored as paper records.
• Lot of man power involved for this job and maintained lot of papers.
• Lot of time was wasted when searching any data.
1.2 1950’s and early 1960’s
• At this period data processing using magnetic tapes for storage.
• Tapes provide only sequential access.
• On this time, using punched cards as input method.
1.3 Late 1960’s and 1970’s
• Hard disks allow direct access to data.
• Data stored in files.
• Between this period introduced File Processing System.

1.4 1960’s
Hierarchical Model
• Well suited for data which are in some way related.
• Hierarchically begin with a strictly defined tree of data nodes.
• Each node can contain some identifying data, plus a set of sub nodes of a specific child

This leads to high level of data redundancy. Due to this valuable storage space is a wasted. Same data may have to be input several times to update all occurrences of a data item. Several versions of the same data may exist.
• Inconsistent Data
When same data is stored in multiple locations inconsistencies may occur. Inconsistencies in stored data are one of the most common sources of errors in computer applications. They lead to consistent documents and reports.
• Inflexibility
A file based system cannot respond to requests for new or redesigned product. Application systems can not readily satisfy demands for information in a format that was not anticipated.
• Limited Data Sharing
With traditional applications approach each application has its own private files and users have little opportunity to share data outside of their own applications.
• Poor Data Control
There is no centralized control for overall data within information systems in file approach. Standards are required for data names, formats, and action restrictions. Data standards are difficult to enforce in a traditional file processing environment. Two types of inconsistencies may result from poor enforcement of standards as synonyms and