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Data on a Touch Pad

RDBMS FUNDAMENTALS

DATA STORAGE APPROACH or RECORD KEEPING SYSTEM

•    The technique used to store data and information manually or electronically in paper, files or database for future use is called as data storage approach.
•    Types of data storage approach:-
    i.     Manual data storage approach
    ii.    Computerized/electronic data storage approach

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Manual data storage approach

•    The process of storing data and information manually by using pen and paper is called as manual data storage approach.
•    In this approach, the human brain is used as a processor.
•    Here data processing speed is slower.
•    There may be more chances of errors.
•    Example:- hand written notes.

Computerized data storage approach

•    The process of storing data and information electronically on a computer in the form of files and database is called as computerized data storage approach.
•    In this approach, the CPU is used as a processor.
•    The data processing speed is very faster than manual data storage approach.
•    There is no or less chances of errors.
•    Example:- word file, excel file, access file, etc.
•    There are two types of computerized data storage approach:-
    a.    File based system
    b.    Database system

File based system

  • It is a computerized data storage approach that stores data in the form of files.

  • A file is a collection of related records.

  • Here data can be stored and accessed sequentially.

  • Example:- it.txt

Database system

•    It is a computerized data storage approach that stores huge amount of data in the form of tables.
•    A database is a collection of related tables.
•    Here data can be stored and accessed centrally or randomly.
•    Example:- college.db
•    A database system stores huge amount of data in tabular format.
•    A table is a collection of related records consisting of rows and columns.
•    Rows are called as records or tuples and columns are called as fields or attributes.

Disadvantages of file based system

  • Non-persistence:-

           In file base system data may be lost due to human error, operational error, etc. so that it is non-persistence.

  • Non-sharing:-

           In file base system a single piece of data can’t be shared among different users at a time.

  • Inaccuracy:-

           In file base system, data may not be accurate due to typing error.

  • Redundancy:-

           -Redundancy means duplicacy of data.

           -In file base system each object may have more than one values.

  • Non-integrity:-

           -No-integrity means inaccuracy and invalidity.

           -Here data can be modified or altered unauthorizedly. So there is a chance of the loss of original data.

  • Inconsistency:-

            Here data may be inconsistent because when data move from one place to another place of a file it may not be             consistent before and after transaction.

  • Slow access/retrieval:-

            In file base system, data can be accessed sequentially one after another. So that it has slow retrieval of data.

  • Insecurity:-

            In file base system, data may be modified or accessed unauthorizedly by outsider. So that data are insecure.

  • Data dependence:-

            In file base system, data its associated application are dependent with each other.

Advantages of database system

  • Persistence:-

          -Persistence means permanent.

          -In database system, data and information are permanently stored for a long time.

  • Sharing:-

          In database system, a single piece of data can be shared among different users at a time.

  • Accuracy:-

          In database system, data always accurate because it is automatically updated.

  • Non-redundancy:-

          -In database system, there is no duplicacy of data.

          -In database system, each object has a unique value.

  • Integrity:-

          -Integrity means accuracy and validity of data.

          -Here data can’t be altered unauthorizedly. So that there is no loss of data.

  • Consistency:-

          Here data is always in consistent state, because when data move from one place to another place of a database it must be consistent before and after transaction.

  • Fast access/retrieval:-

          In database system, data can be stored and accessed randomly at any part of database. So that, it has fast retrieval of data.

  • Security:-

          -In database system, data can’t be manipulated unauthorizedly by any outsider. So that data are secure.

          -It allows only to valid users to access data.

  • Data independence:-

           In database system, data and its associated application are independent to each other.

Disadvantages of database system

  • It requires high installation cost.

  • It requires high maintenance cost.

  • It needs computerized expert person.

  • It needs periodical back up of database to recover from damage or loss of data.

Parts of database system

  • A database system consist of two parts:-

  1. Database application

  2. DBMS

Database application

  • It is a program used to store, access and manipulate data stored in a database.

  • It consists of users who use the database.

  • Example:- online examination system, banking system, railway reservation system, etc.

DBMS

  • It stands for Database Management System.

  • It is a software used to create, manipulate and manage a database application/system.

  • It is responsible for maintenance of the database application.

  • Example:- My SQL, ORACLE, MS-Access, etc.

Function of DBMS

  • A DBMS performs following four functions:-

       i.    Creation of the database.

       ii.   Insertion of data into the database.

       iii.  Manipulation/access of database.

       iv.  Generating report/result of the database.

Features of DBMS

  • There are following features of DBMS:-

         a. Transaction processing

         b. Concurrency control

         c. Recovery/back up

         d. Language interface

         e. Data dictionary

         f. Storage management

         g. Data security

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Transaction processing:-

  • A transaction is a small unit of logical work performed on database.

  • A DBMS uses a COMMIT statement to make sure that any changes made by the transaction are permanent.

  • When a DBMS uses ROLLBACK statement then the database returns to previous consistent state.

Concurrency control:-

  • In database system, a number of transactions are running simultaneously to perform  different operations.

  • In DBMS process all the transactions running concurrently without interfearing with each other.

Recovery:-

  • A DBMS takes periodical back up of the database monthly, quarterly, annually, half yearly.

  • It can recover the database from any loss due to hardware failure, software failure or disaster.

Language interface:-

  • A database uses its own language to interact with database application.

  • SQL is the database language used to interact with database.

Data dictionary:-

  • A data dictionary is a catelouge system that contains data about data (metadata).

Storage management:-

  • A DBMS decides how, when and where data can be stored and accessed to and from database.

  • It is responsible for storage management of the database.

Data security:-

  • A DBMS ensures the security of the database.

  • It provides a valid user ID and password to allow authorized user to access data from database.

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