Introduction of DBMS

As the name suggests, the database management system can break it like this.   

 DBMS = Database + Management System.

“Database is a collection of Data. And Management System is a set of programs to store and retrieve those data.”

Why DBMS?

Database systems are basically developed for large amount of data. When dealing with huge amount of data, there are two things for require optimization: Storage of data and Retrieval of data.

What is Data?

Data is a collection of raw facts, whereas raw facts is means “the collection of numbers, words, special Symbols and figures.

“Data never provide the meaningful statements.”

 What is Table and Record?                                            

Collection of related records, is called Table.

Collection of related data items is called Record.

 Example: Below given table contains three data items had no meaning. But if we organize them in the following way, then they collectively represent meaningful information.

                  

What is Information?

Processing the Data is called as information.

“Information always provide the meaningful statements to the user.”

What is a Management System?

A management system is a set of rules and procedures, with the help of you can create, organize and manipulate the database. It also helps us to insert, select, modify and delete data items in the database. The management system can be either manual or computerized.

The management system is important because without the existence of some kind of rules and regulations. It is not possible to maintain the database. We have to select the particular attributes which should be included in a particular table, the common attributes to create a relationship between two tables, if a new record has to be inserted or deleted then which tables should have to be handled etc.. These issues must be resolved by having some kind of rules to follow, in order to maintain the integrity of the database.

What is User?

“A user is a person who uses a computer or network service. Users generally use a system or a software product without the technical expertise required to fully understand it.”

The users of a DBMS can be broadly categorized as follows −

1. Database Administrator (DBA): DBA takes care of the administrative tasks of DBMS as the name suggests and his major responsibilities are given below.

(1) Management of information

(2) Liaison with users

(3) Enforcing security and integrity rules

(4) Database backup and recovery

(5) Monitoring database performance

2. Database Designers: Database designers design the database components

3.Application Programmers: Application programmers write programs to access/insert/  update /delete data from the database by making use of the various database components.

4. End Users: End users use DBMS.

                    

What is a Database?

A Database is a computer based record keeping system which is used to record, maintain and retrieve data. It is an organized collection of interrelated (persistent) data.

What type of data is stored in the database?  

             

In a database, we would be grouping only related data together and storing them under one group name called a table. This helps in identifying which data is stored where and under what name. It reduces the time to search for a particular data in a whole database. For example, Student, Teacher, Class, Subject, Employee, Department etc. form individual tables.

Types of Databases:

There are two types of database:

1.       Centralized Database

2.       Distributed Database

      1.  Centralized Database: In Centralized database system, all data is stored at a single site. It offers a great control in accessing and updating data. However, failure chances are high because the system depends on the availability of resources at the central site.

          Example:

• Some major banks do all their processing on a mainframe, in some cases in a different country.
• Clients may use several Airline reservation systems need to be centralized to avoid double bookings.
• Airline reservation systems need to be centralized to avoid double bookings.

             

Advantages:

•         Increased reliability and availability
•         Modular (incremental) growth
•         Lower communication costs
•         Faster Response

Disadvantages:

•         Software cost and complexity
•         Processing overheads
•         Data integrity

2. Distributed Database: In Distributed Database system, the database is stored on several computers. Computers in a distributed system may communicate with one another through internet/intranet/telephone lines etc. Most of the distributed systems will be geographically separated and managed. Distributed databases can also separately be administered.

         Example:   Telephone Network and Cellular Networks.

   Advantages:

•         Minimize communications
•         Costs
•         Local control

   Disadvantages:

•         Adds to complexity and cost
•         Processing overheads
•         Data Integrity

DBMS

What is Database Management System?

“DBMS is a tool or software which can be used for managing and maintaining data in the database.”

We can define DBMS like this:

A DBMS is a collection of interrelated data and set of programs to store & access this data in an easy and effective manner.

             

Advantages of a DBMS:

•         Data independence
•         Reduced data redundancy
•         Increased security
•         Better flexibility
•         Effective data sharing
•         Enforces integrity constraints
•         Enables backup and recovery.

Disadvantages of a DBMS:

•         Cost of Hardware and Software
•         Cost of Data Conversion
•         Cost of Staff Training
•         Appointing Staff
•         Database Damage

  Services provide by a DBMS :

•         Data management
•         Data definition
•         Transaction support
•         Concurrency control
•         Recovery
•         Security and integrity
•         Facilities to import and export data
•         User management
•         Backup
•         Performance analysis
•         Logging
•         Audit
•         Physical storage control

Difference between File based Data Storage System and DBMS:

             

Models of Database Management System:

DBMS contain the following Six Models:

1. File Management System (FMS)

2. Hierarchical Management System (HMS)

3. Network Database Management System (NDBMS)

4. Relational Database Management System (RDBMS)

5. Object Relational Database Management System (ORDBMS)

6. Object Oriented Relational Database Management System (OORDBMS)

1. File Management System (FMS): FMS is a first model of the database which was introduced in 1950’s, in this model data will be stored a sequential manned continuing stream of characters' manners. Ex.

             

Drawback :

•         This is no security to file information.
•          He does not support data type & index mechanism.
•         To maintain data in consistency(is no proper order)

2. Hierarchical Management System (HMS): Hierarchical Management System is a second model of the database which was introduced IBM, where developing a project a project is called as information management system in 1950.

In this model, the data will be store in the form of free structure and it contain the following levels:

.       The Root: It will represent database location in DB name.

      The Parent: It will represent table/entity name.

      The Child: It will represent columns/attribute name.

             

           

Drawback :

•       In this model only one person interact with the database server simultaneously at a time.
•      If we add a new value to at existing structure then the user has to recon structure the entire  structure.
•      This process will leads time consuming and burden of the programmer will be  increased

 

Advantage:

•          Its support Data Type & index mechanism.
•        To maintain consistency of the data (Arranging the values systematized)
•        Retrieving data is faster than FMS Model.

3. Network Database Management System (NDBMS): Network Management System is a third model of the database which was introduced IBM in 1969.

In this model the data will be stored in the form of free structure and integrated with network of environmental.

             

 Drawback :

•          There is no proper security of the centralized DB (CDB) Server.
•          The Database will be increased (increasing duplicate value).
•          Mode memory will occupy.
•          The application system is performed will be reduced.

  Advantage:

•        In NDBMS model multiple user can interact with the DB at a time and also                multiple users can store the data at a time.
•          If we add a new value into an existing structure by using Pointer.

NOTE: "The above, all models are outdated industries in real time."

4. Relational Database Management System (RDBMS): RDBMS is a relational model           which words introduce parts, which was German Scientist Mr. E.F. Codd in 1970’s.

Here Relation can be defined as the normal test between objects, If any database which will be stored, the form of a popular format. The database is a formal RDBMS protector.

The relation can divide into three types:
(1) One to One Relation
(2) One to Many Relation
(3) Many to Many Relation

(1) One to One Relation: A row in a table, each associated with a row any at the other table, there is known as One to One Relation.

(2) One to Many Relation: A row in a table, each associated with a many rows in at another table, there is known as one to Many Relation.

 (3) Many to Many Relation: Many rows create a table, each associated with a many           rows in at another table, there is known as many to Many Relation.

The about three models called “degree of relationship”, which was developed by case of mathematical concepts, these corners Relational Algebra in 1970's.

List of RDBMS Products:

There  are most popular in RDBMS Product is:

•    SQL Server
•    Oracle
•    MySQL
•    DB2
•    PostgreSQL

      etc..