What is Database Management System and It's Objectives

What is Database Management System and It's Objectives, Database Model, Relational Database Management System (RDBMS), Concept of Normalization

A database is a repository for a collection of related data or faces. The Most obvious example of the non-computerized database is a telephone directory database programs can also sort a list of data arranging them in alphabetical, numeric or chronological order and can search or query data with different conditions. 

What is Database Management System and It's Objectives

Data and Information

The word data is used to refer to a fact or concept. The data and the information are not the same things. Data arranged in certain order and form which is useful to us is called information. Data is the raw material to generate information that is data is to be processed to produce information.

Database Management System (DBMS)

Database Management System (DBMS) is software that defines a database, stores data, supports a query language, produces reports and creates data entry screen. Database systems are designed to manage large bodies of information.

Objective of DBMS

DBMS applications must be capable of solving challenging problems of different an organizations. some objectives of DBMS are given below
  • Provide for mass storage of relevant data 
  • Making easy access to data for the authorized user. 
  • Providing prompt response to users requests for data. 
  • Eliminate redundantly (Duplicate) d data. 
  • Allow multiple users to be active at one time. 
  • Allow the growth of database system 
  • Provide data integrity. 
  • Protect the data from physical harm and unauthorized access. 
  • Serving different types of users. the
  • Provide security with user access privilege. 
  • Combining interrelated data to generate report
  • Provide multiple views for same data. 

Database Model

Database models are used to organize data it determines the manner in which data can be stored, organized and manipulated in a database system.
Hierarchical Database Model: - Hierarchical database is the oldest model of database. We frequently find data exhibiting a hierarchical (Level or tree structure) relationship. Database system must start from the top (also called root).

Advantage1. Easiest model of database.
2. More Secure because nobody can see and modify a child without consulting
3. Searching is fast and easy if parent in known.
4. Efficient in handling one to much relationship.
Disadvantage1. It is old fashioned.
2. Modification and addition of child without consulting the parent is impossible or very hard.
3. It is nonflexible database model.
4. Can't handle many to much relationship.
5. Increase data redundancy.

Network Database Model: - Network database model is network of connections between data elements are established this model overcome s the problems faced in hierarchical model searching data from bottom or middle.
Advantage
1. It is more flexible.
2. Less data redundancy.
3. Support many to much relation.

Disadvantage
1. It takes more space.
2. More processing time.

Relational Database Model: Relational Database model is a collection of data items is organized in table from which data can be accessed in May different way this model can handle many to many relationship.

Advantage
1. Flexible and efficiency
2. Relationship many to many
3. Table Diagram
4. Good Management
5. Less Redundancy
6. Searching speed is fast

Disadvantage
1. Very complex
2. Not- User friendly
3. Less Secure

Key Terms to be known in database system

Fields: - Fields contain one piece of information of an entry in database example: - is and address book each entry has fields for first name last name, address phone number email birth day etc.

Record: - One full set of fields i.e. All the related information about one person or object is called record.

Table: - A complete collection of record is called a table. A table contains rows and columns. Each column of a table represents a field and each row represents a record.

Relational Database Management System (RDBMS)

The DBMS in which relation between different tables can be formed using a common field or attribute in those tables to draw relations in between is called Relational Database Management System. Relational Database implements data in a series or two- dimensional table that is related to one another through foreign key.

Concepts for Relational Database System

Entity: - An entity is a class of persons, place, events, objects or concept in the real world that is distinguishable from other objects. Entity is also called entity type or entity class.

Attributes: Attributes are descriptive properties possessed by each member of an entity. Arrtibures are also called element, property of field.

Relationships: - A relationship is nature business association that exists between one or more entities. The relationship may represent and event that links the entities. 

Concept of Normalization

Normalization is the process of splitting table to minimize data redundancy and establishing relation between tables. It is must be carefully designed in order to get full advantages It is provides flexible, data consistency and avoids anomalies while inserting, deleting and updating data.

Forms of Normalization

There are six normal Forms but in practice first, second, and third normal forms are widely used.

1. First Normal Forms (1Ne): - A table is said to be in first normal form if it has no repeating groups. That is for each cell in a table, there can be only one value. It is flexible handle one to many relationship, less space.

2. Second Normal Form (2Ne): - A table said to be in second normal form if it is already in first normal form and if every non key column depends on the entire key.

3. Third Normal Form (3Ne): - A table is said to be in third normal form if it is already in second normal form and if non key columns are not dependent on each other.

Database Administrator (DBA)

A database administrator is the individual responsible for maintaining the DBMS It has many different responsibilities, but the overall goal of DBA is keep the serve up t all times. It can be someone who has concentrated in he areas of database design and administration. A DBA can be a programmer who took the responsibility of maintaining a database server.

A DBA Need the following. 1. Knowledge of the operation system in which database server is running.
2. Knowledge of database design.
3. Knowledge of structure query language
4. Knowledge about the database server.
5. General understanding of network architectures example:- client/ server, internet/ Intranet.

Roles and Responsibilities of DBA

Installing and Upgrading database server
The DBA is responsible for installing database server or upgrading and existing database server. In the case of upgrading database server, the DBA is responsible for ensuring that if the upgrade is not successful.
Monitoring the Database Saver's Health and Tuning Accordingly: - The server is running with optimal performance. The error log or event is monitored for database errors.
Using Storage properly; - Database server's enable us to automatically grow the size of the database and transaction logs, or we can choose to select a fixed size for the database and transaction log.
Performing Backup and Recovery Duties: -  Establishing standards and schedules for database backups

Developing recovery procedures for each database. - Making sure that the backup schedules meet the recovery requirements.
Managing Database Users and Security: - The DBA works tightly with the network administrator to add network users to the database.
Working with Developers: - The DBA work closely with development teams to assist in overall database design.
Transferring data: - The DBA is responsible for importing and exporting data to and form the database server. 

Scheduling events: - The DBA is responsible for setting up and scheduling various events. 

Establishing and Enforcing Standard 
Replicating Data
Providing 24 hour access 
Learning constantly 

Types of Database

1) Centralized Database: - Centralized Database works on a client sever basis. The Consoling mechanism is also centralized and data are deposited in a central location. Files kept on the basis location of disk drive & names. It is suitable for small organization and small scale operations.

Advantage: - Easy to maintain
Disadvantage: - If the server is destroyed by some catastrophic damage like flood fire whole data is lost.

2) Distributed Database : - Distributed database is dispersed across many geographical location. Data communication is harder because they should communicate through different system to different platforms security is most crucial part of this database.

Distributed system offers a lot of advantages 1. Distributed system is much cheaper than centralized system less expensive hardware is used.
2. It allows us to store copies of data at different location.
3. In distributed system, the problem in one location will not affect entire system.

Data security: - Data security is and importance issue in every organization, big or small for maintaining database system data security is a method of keeping data protected from corruption and unauthorized access and ensuring privacy.

Two method of data security
1. Physical Security: - Physical security is concerned with physical aspects such as protecting computer resources preparing for physical disasters of catastrophic damage. 

2. Logical Security: - Logical security is concerned with protecting the data and controlling access to data.

Advantage of DBMS
1. Data sharing
This is most importance and biggest benefit all authorized user can work with the same set of data.

2. Reduced Data redundancy
Data redundancy means that same data fields show in May different files and often in different formats.

3. Improved data Integrity
Data integrity means that data accurate consistent and up to data. In a DBMS reduced redundancy increase data integrity. 

4. Increased Security
Various departments may share data; access to specific information can be limited to selected uses.

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