DBMS Principles for Dummies

Topics what must to know for DBMS Developments. 

1. Introduction to Database Management System
2. DBMS vs. File System
3. Advantages of DBMS
4. Disadvantages of DBMS
5. Components of Database Environment
6. Functions of DBMS
7. Database Languages

Introduction to Database Management System

• Data is the presentation of facts, information, or concepts which are created in a computer readable form or translated into such a form.
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• A database is a collection of information that is organized for easy management, update and access.
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• A Database Management System (DBMS) is a software package designed to create, store, and manage databases.

A database management system is a set of software programs that allows users

• To create, edit and update data in database files
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• To store and retrieve data from those database files

DBMS allows organizations to control database development by database administrators (DBAs) and other specialists.

A collection of data viewed by the operator as somehow going together, plus additional data which is used by the DBMS in order to work correctly is called a “database”.

DBMS vs. File System

• Files act locally
• DBMS saves directly in a database
• Saves in temporary locations
• Well-arranged and permanent data base locations
• Transactions are not possible
• Transactions like insert, delete, view, updating etc. are possible
• Data will be accessed through single or various files
• Tables (schema) are used to access data
• A "File manager" is used to store all relationships in directories
• “Database manager” (administrator) stores the relationship in the form of structural tables

Advantages of DBMS

• Reduced data redundancy.
• Reduced updating errors and increased consistency.
• Greater data integrity and independence from applications programs.
• Improved data access to users through use of host and query languages.
• Improved data security.
• Reduced data entry, storage, and retrieval costs.
• Facilitated development of new applications program.

Disadvantages of DBMS

• Database systems are complex, difficult, and time-consuming to design.
• Substantial hardware and software start-up costs.
• Damage to database affects virtually all applications programs.
• Extensive conversion costs in moving from a file-based system to a database system.
• Initial training required for all programmers and users.
• Components of Database Environment

Following are the components of a database environment:

• CASE Tools
• Repository
• DBMS
• Database
• Application Programs
• User Interface
• Data Administrators
• System Developers
• End Users
• CASE (Computer Aided Software Engineering) Tools. CASE tools are automated tools used to design databases and application programs.
• Repository : Repository is the centralized storehouse of metadata. Metadata is the data that describes the properties or characteristics of end-user data and the context of that data.
• DBMS:DBMS is a software system used to create, maintain, and provide controlled access to user databases.
• Database : Database is an organized collection of logically related data.
• Application Programs: Application programs are used to create and maintain the database.
• User Interface: The user interface represents the languages, menus and Graphical User Interface by which user interacts with the components of the system.

Data/Database Administrators

Database administrator coordinates all the activities of the database system.

System Developers

System developers are concerned with the designing of the new application programs.

End Users

End users are the people who use the applications and databases.

Functions of DBMS

The database management system performs following functions:

DBMS serves as a component that preserves the relationship among different related records in the database. It helps to reduce data redundancy and increase consistency.

• Concurrency : Concurrency means preventing two users from interfering with each other when they use the same information.
• Security : DBMS has components that limit access or actions to reduce potential damage to data. Security rules determine the access rights of the users.
• Backup/Recovery : The DBMS provides backup and recovery processes to confirm and repeat transactions so that database can be restored to a valid state after a problem.
• Data Dictionary: Data dictionary contains data about each file in the database and each field within those files. Data dictionary provides the description of the data to enable program-data independence.
• Database Languages: A database supports a number of user groups, thus, the DBMS must have languages and interfaces that support each group.

There are two database languages that make the database system:

• Data Definition Language
• Data Manipulation Language
• Data Definition Language
• Data Definition Language is used to define and modify (rename, alter, drop, create) the structure of database.
• Data Manipulation Language
• Data Manipulation Language is used to manipulate (retrieve, insert, update, and delete) the structure of database.