Unit 1 – Database Management System (DBMS)

 Database Management System (DBMS)

Data:

Data is defined as the raw facts and figures. It could be any numbers, pictures, sound, alphabets or any combination of it. Which do not provide clear meaning. Examples, 101, Hari, Bharatpur etc.

1.      Primary Data: Facts and figures newly collected. Examples, observation data, questionnaire data, surveys data etc.

2.      Secondary data: Facts and figures already collected. Examples, Financial statements, customer list, sales report, census report etc. 

Data Processing:

Data processing is the mechanism of converting unprocessed data into meaningful result or information.

Information:

When data are processed using a database program or software, they are converted to the meaningful result, called information. Information provides answers to "who", "what", "where", and "when" questions. Examples, Hari lives in Bharatpur-11, Chitwan.

 

Data Processing 

Difference between Data and Information

 

S.N.	Data	S.N.	Information
1	It is raw or known facts.	1	It is processed or refined data.
2	It stores the facts.	2	It presents the facts.
3	It is inactive in nature (they exist)	3	It is active in nature (It enables doing)
4	It is technology-based	4	It is business based
5	Data is gathered from various sources.	5	Information is transformed from data
6	Data do not have fixed format.	6	Information normally in the form of table, graph, curve line etc.

 Flat File/ File based system:

•      It is traditional way to keeping records of any organization in a manual filing system. It means to used to keep records in file based or flat file system non computerized.

•      A flat file system is a system of flies in which every file in the system must have a different name.

 

Limitation of file based/ Flat file system

•  Duplication of data ( DataRedundancy)
•  Inconsistent data.
• Program Data dependence.
• Poor data control.
• Limited data sharing.
• Security problems.
• Incompatible file formats.
•  Fixed queries 

Database System:

A database system consists of a collection of interrelated data and a set of application programs to access, update and manage the data.

Database:

It is organized form of record about some person, organization or something store under certain media. It is a collection of related information about a subject organized in a useful manner that provides a base or foundation for procedure, such as retrieving information, drawing conclusion and make decision.

Advantage of database over flat file or file based system

1. Reduction of data redundancies
2. Shared data
3. Data independent
4. Improved integrity
5. Efficient data access
6. Multiple user interface
7. Improved security
8. Improved backup and recovery
9. Supports for concurrent transactions
10.  Unforeseen queries can be answered 

File based system Vs Electronic Database System

 

S.N.	File Based System	S.N.	Electronic Database System
1	It provide detail of the data representation and storage of data	1	Database System gives abstract view of data that hides details.
2	It doesn’t have a crash recovery mechanism.	2	It provides crash recovery mechanism using backup and other security measures.
3	It is difficult to reduce data redundancy.	3	Data redundancy can be done easily.
4	Searching of data requires a lot of time and effort.	4	Data can be easily searched.
5	Difficult to maintain the database.	5	Easy to maintain the database.

DBMS:

Database Management System is software that manages the data stored in a database. This is a collection of software which is used to store data, records, process them and obtain desired information. Since, data are very important to the end users, we must have a good way of managing data.

A DBMS is a collection of programs that manages the database structure and controls access to the data stored in the database. The DBMS make it possible to share the data in the database among multiple applications or users. The DBMS stands between the database and the user.

    Examples: MS-Access, Oracle, FoxPro, dBase, SQL server, MySQL, Delphi, Sybase, etc. 

Why to Use DBMS?

1.      To develop software application in less time.

2.      Data independence and efficient use of data.

3.      For uniform data administration.

4.      For data integrity and security.

5.      For concurrent access to data, and data recovery from crashes.

6.      To use user friendly declarative query language.

 

Some major database System activities are (Functions of DBMS)

1.      Adding new file to the database

2.      Inserting data into the database

3.      Retrieving/viewing data from the database

4.      Updating data in existing database file

5.      Deleting data from the database file

6. Removing files from the database 

 Advantages and Disadvantages of DBMSAdvantages of DBMS

1. Sharing Data: Data stored in a database can be shared. It refers to the capacity that makes data simultaneously accessible by many users without any interference.
2. Reduced data redundancy: The same data may be duplicated at many times or places, is called data redundancy. DBMS reduces such type of duplication of data from database.
3. Data backup and recovery: DBMS provides backup facilities to store data for future use. If any files or data lost in any computer, it is possible to restore them from database server.
4. Inconsistency avoided: When the same data is duplicated and changes are made at one site, and mot on other sites, it causes data inconsistency. DBMS avoided such type of data inconsistency.
5. Data integrity: Data integrity means data accuracy, consistency and up to date. A DBMS should provide capabilities for defining and enforcing constraints for data integrity.
6. Data Security: In database system, an unauthorized person cannot access data from database. Although various departments may share data in database, access to specific information that can be limited to selected users.
7. Data independence: Description of the data(Schema) is stored in one central place. Therefore, applications do not have to recompile when the format of the data changes.
8. Multiple user interfaces: DBMS provides variety of interfaces for various users. It provides query language interface, forms and command interfaces so that users interact easily with the database.
9. Process complex query: It provides different methods such as view, trigger, index etc. to process complex queries.

Disadvantages of DBMS

1. Expensive: Database software is very expensive for large computer systems. It also requires overhead costs for maintaining and integrity functions.
2. Changing technology: It is fast changing technology.
3. Needs Technical Training: It is complex to understand and implement. So, proper training is required for staff to work properly in the database system.
4. Backup is needed: It needs to explicit backup. This adds costs as new storage space are needed to hold the data.