Before we start with DBMS we should know what is data. A data is a piece of information, and database is the collection of data that is set in an orderly way. And managing this database is known as Database Management System in short DBMS. The person who manages, creates, controls and maintain this database management system is known as Database Administrator (DBA). Another important term to remember is information. Any data which has been converted to a useful and understandable form is called information.
There are some differences between data and information.
Data
Information
Any raw figure or fact is data.
For example 6 is a data.
A processed form of data is known as information.
For example weight = 6 kg is data
Data does not help in making decisions.
With right information we can make decision.
Functions of Database Management System
Data Modeling: The structured definition of data storage is known as data modeling.
Processing Query: This a mechanism of manipulating the data
Concurrency Control: To ensure the accuracy and simultaneous access of the database by multiple users.
Security of Information: Security of the database is very important.
Crash Recovery: Data recovery after the system crashes.
Types of Database users
Database Administrator (DBA): The database administrator is the person who who maintains designs and creates the database.
Database Designer: A database designer is a person who plans or designs the database.
End User: The one who uses the database, it may be that he/she only views the database or it may be that he/she makes the data entries. Make queries, etc
There may be different types of end user, for example:
Sophisticated: these are the users who has a good knowledge in database and can make queries, with SQL manipulate data with DML (Data Manipulating Language)
Specialized: who makes application programs that interacts with the database
Native: only interacts with the database via some sophisticated programs
Application Programmers: A person who makes applications which interacts with the database using programming language like C++ , Java, etc. He may create a software which gives a easy to use interface to input data into a complex database, so that even the clerks of the office can input data or search for some data from the companies database without knowing Oracle, MySQL or other DBMS software
Database Model
Database Model is the structure or the format of the data; it may be physical or conceptual. Database Model is also known as database schema.
Conceptual Model: Conceptual Model helps to overview the organizational schema rather than the database schema.
Physical Model: Physical Model is the database design which means that this model describes the data storage, data structure, etc. basically we get to know about the physical media of the data storage and the mode of access of that data from this model.
Frame Memory Model: This type of model is generally used for large manufacturing database application. Modifying the characteristic of the complex database easily and accurately.
Unifying Model: in the Unifying Model the Entity-Relation concept has been extended to introduce a new form of diagrammatic representation other than class diagrams.
Object Oriented Model: A Object Oriented Model is a data model in which the real life data or entities are organized. Generally Object Oriented Data Model or OODM consists of the following concepts, they are as follows:
Object and object identifier
Attributes and methods
Class
Class hierarchy and inheritance
Record Based Model: The Record Based Model helps us to specify the overall logical structure of the database. In this type of data bases the numbers of types of data are fixed. And each of the record type or data type has a fixed number of fields with fixed field length. There are three types of record based data model they are:
Hierarchical Model: In a Hierarchical Model the data is organized in a form of tree like structure. In this kind of structure the parent — child relationship can easily be shown. A very famous use of this kind of database is the Windows Registry developed by Microsoft.
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Network Model: This is a type of database model where it is easy to represent objects and relationship. Its more easier to define many to many relation in this model rather than in the hierarchical model. A well known implementation of Network Model is RDM Server.
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Relational Model: The relational model was developed by E.F Codd. The properties of a relational database model are as follows:
The columns of table are all homogenous i.e. they are of the same kind.
Every item should have simple value.
All the relationship of tuples must be distinct.
The key value should be used to order the tuples within a relationship.
Columns are named distinctly and their ordering is not so important.
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Manual Database.
A Manual Database is a record kept by a human without the use of any computers or electronic devices. This obviously has many problems like:
Searching: It is very difficult to find a particular result from a manual database if the size of the database is huge.
Updating: Updating a new entry is also problematic as we have to manually find the old record, scratch it, or erase it then make the new entry.
Backing up: Suppose there is a database of 10,000 pages making a manual backup of this database, i.e. a handwritten copy of it will be difficult to make.
Sorting: It is virtually impossible to sort the data say names of customers by alphabetic order, etc on a manual database.
As we see that making a manual database of a large amount of data becomes impossible to manage so now we use computerized data.
Traditional File Processing System
One of the earliest forms of computerizing data storage is the file processing system. Creating, sorting, organizing and accessing the content of the file is known as File Processing System.
Characteristics of File Processing System.
Each file is different from each other.
This is a collection of files, or sorted data.
Each of the file is called a flat file.
Every file contains processed information of a specific function such as one file may be for accounting other file may be of contacts.
Files are created by the help of program which are written in C, C++ or COBOL.
Drawbacks of the File Processing System.
There are many drawbacks of File Processing System.
Separated Data
Duplicated Data
Data Dependency
Data inflexibility
Problems in representing the data to user.
File format problems.
Database: A database is a organized form of data. This organization is very important because when the size of data increases it becomes difficult to use or control the data.
Database Management System: A DBMS or Database Management System is a collection of data and programs which help us to access and modify those data. The collection of data is called database. The main purpose of DBMS is to efficiently store and control the database.
Advantages of DBMS
Control Redundancy: With the help of DBMS data redundancy can be controlled. In the File Processing System there used to be data redundancy, which means that the same data stored more than once.
Integrity: Maintaining Integrity means that the data stored in the database is accurate and precise. This is very much important as incorrect data can not be stored into the database so some integrity constraints are enabled on the database, to check the accuracy of the database.
Avoiding inconsistency: Consider there are two data storage sites of data and some changes are made in one site but those changes are not reflected on the other site for some reasons then it gives rise to data inconsistency. To avoid this data redundancy should be removed if data redundancy is checked it will also remove data inconsistency.
Data Sharing: Suppose a same data is required by two databases then that data can be shared from a centralized database.
Maintaining standards: As we know that DBMS is a centralized system so it can be standardized effectively. A company database can be standardized in Department Level, National Level, International Level, etc.
Preventing unauthorized access: Lots of security can be enabled to prevent the unauthorized access of the data. Passwords and encryptions are enabled in database to provide better security to company’s data.
Backup and recovery of data: Data loss can happen at any moment due to number of reasons so it is very much important to create backup so that the data can be recovered if there is any accidental loss of data.
Disadvantages of DBMS
Complexity: The functionality of DBMS is a very complex process. The database designer, database administrator, developer and the end user should have a clear understanding of the DBMS working and functionality to make it work in a correct way. If they fail to do it DBMS will not work in a proper way.
Size: As time passes the size or the volume of data increases which makes the size of database larger. Moving, copying and editing this large amount of data take a considerable time and system resource. Sometimes upgrading RAM or Disk Space becomes necessary to run the DBMS properly
Performance: DBMS software tends to run slower than the typical File Processing System.
Cost: Cost of implementing the DBMS is high. Sometimes the DBMS software for the specific environment is high, or the upgradeing of hardware to run it becomes costly or when converting from an older system to DBMS the process of conversion of the data costs a lot.
Failure rate higher: As it is a centralized system I it fals every operation comes to a halt.
Difference between File Management System and Database Management System
File Management System
Database Management System
File management Systems are relatively small in size and volume
Database Management Systems are comparatively larger in size.
They are cheaper to implement
Much costlier to implement
It deals with few files
It deals with a large number of files.
The structure of this system is very simple
The structure is very much complex in nature.
There are many redundant data.
Redundant data is very much reduced.
Data inconsistency takes place in File Management System
Data inconsistency is checked in the DBMS
In File Management System data is isolated.
In DBMS data can be shared.
There is no security.
It is secured.
Very simple and primitive form of backup and recovery.
Highly sophisticated and complex form of backup and recovery.
Mainly single user.
Most of the time its multiuser.
Less preliminary design
Vast preliminary design
Purpose of DBMS
Database Management System is very useful and is used in many sectors. Some the areas where it is used is given below.
Railway: for making the railway enquiry and reservation system to work properly there is a needed of implementing DBMS as all the data has to be stored in a centralized location and the data is then used by every railway stations throughout the country.
Banking: As now a days there are many branches of a bank there has to be a DBMS to track and record the transactions of every customers. This will have not been possible if File Management System were used.
Schools/Colleges and Universities: To store the records of students like their name, roll number, address, contact number, marks obtained, etc a DBMS is used so that the database can be updated easily.
Business and Offices: To store the company’s sales, profit , etc and its record of employees a sophisticated DBMS is used.
Instances and Schemas
The database changes from time to time, the information which is stored in the database at a particular time is known as Instance. A Schema is a overall design of the database .
QUESTIONS
What do you mean by DBMS?
A DBMS or Database Management System is a collection of data and programs which help us to access and modify those data. The collection of data is called database. The main purpose of DBMS is to efficiently store and control the database.
How does DBMS differs from MS Excel?
What are the differences between data and information?
What is the difference between Conceptual Model and Physical Model?
Conceptual Model: Conceptual Model helps to overview the organizational schema rather than the database schema.
Physical Model: Physical Model is the database design which means that this model describes the data storage, data structure, etc. basically we get to know about the physical media of the data storage and the mode of access of that data from this model.
What are the difference between Traditional File Management System and Database Management System?
Traditional File Management System
Database Management System
File management Systems are relatively small in size and volume
Database Management Systems are comparatively larger in size.
They are cheaper to implement
Much costlier to implement
It deals with few files
It deals with a large number of files.
The structure of this system is very simple
The structure is very much complex in nature.
There are many redundant data.
Redundant data is very much reduced.
Data inconsistency takes place in File Management System
Data inconsistency is checked in the DBMS
In File Management System data is isolated.
In DBMS data can be shared.
There is no security.
It is secured.
Very simple and primitive form of backup and recovery.
Highly sophisticated and complex form of backup and recovery.
Mainly single user.
Most of the time its multiuser.
Less preliminary design
Vast preliminary design
What do you mean by Data Duplicity?
Data Duplicity means repetition of the same data more than once in the same database. Data Duplicity causes lot of problems like:
It is waste of time and money.
It leads to loss of data integrity.
It takes up additional storage and increases the size of the database which effects the search time.
What do you mean by Data Dependency?
In a File Processing System the specific physical format of file and record were hard coded on the application programs. So a change in database format required the codes to be updated.
What is data isolation?
Data Isolation means a data which is isolated form other databases that means when data can not be shared. It is not possible to share data in a File Processing System so the data remains in a isolated condition.
Write down the necessary steps to secure a data into a database.
What do you mean by redundant data?
Data Redundancy means duplication of data. A same data may be present more than onces leading to data inconsistency.
Write down the applications of Database Management System.
There are many applications of Database Management System , some of them are explained below:
Railway: for making the railway enquiry and reservation system to work properly there is a needed of implementing DBMS as all the data has to be stored in a centralized location and the data is then used by every railway stations throughout the country.
Banking: As now a days there are many branches of a bank there has to be a DBMS to track and record the transactions of every customers. This will have not been possible if File Management System were used.
Schools/Colleges and Universities: To store the records of students like their name, roll number, address, contact number, marks obtained, etc a DBMS is used so that the database can be updated easily.
Business and Offices: To store the company’s sales, profit , etc and its record of employees a sophisticated DBMS is used.
Who are the End Users? How many types of End Users are there in DBMS?
End User: The one who uses the database, it may be that he/she only views the database or it may be that he/she makes the data entries. Make queries, etc
There may be different types of end user, for example :
Sophisticated: these are the users who has a good knowledge in database and can make queries, with SQL manipulate data with DML (Data Manipulating Language)
Specialized: who makes application programs that interacts with the database
Native: only interacts with the database via some sophisticated programs
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