Saturday, May 20, 2017

BASIC TERMS USED IN DATABASE MANAGEMENT SYSTEMS

Entity :  Any person or thing which has some characteristics or attributes is called an entity, A person would have different attributes like, name, age,gender, weight, date of birth, place of birth, father's name etc.
 A thing may be a  TV which may have attributes like, make , model no, serial no, year of manufacture,price, date of sale, warranty period etc.

 Table : A table is a chart having multiple columns and rows. Each column shall have a column name. Each row shall hold data related to a particular member which shall be called a record. The picture below shows a typical table. Each table will have data related to a particular  entity.
    
SRL NONAMEAGEGENDERDATE OF BIRTH
1KIRAN 23MALE11/05/1994
2POOJA22FEMALE23/07/1995
3JAIN19MALE05/08/1998
4BHANU25FEMALE12/07/1992
5RUPESH24MALE18/11/1993


 Data type : Data can be in the following types. Some frequently used data types are listed below:

 i)   Characters: Example - a,b,c X ,Y Z etc
 ii)  Strings: Example - Name, Age, Weight etc
 iii) Numbers : Integers Example - 1,4, 56 etc. Real numbers Example - 1.23,
      45.789  etc Exponential numbers 2.34X10^ 3
 iv) Date: Example - 23/05/2017,  Jan 23' 1978 etc


 Database: A Database will have multiple tables. If you consider a Company where people work, we can think of the following tables:

 i) Employee table : Data held- name, age,gender, weight, date of birth, place of birth, employee ID no,father's name etc, date of joining.
 ii) Department table: Department name, department number, employee ID no, designation etc
 iii) Attendance table : date, employee name, employee ID no,present/absent/leave.
 iv) Education and training: SSLC marks, class , year of passing, PUC marks, class, year of passing, diploma/degree marks, class, year of passing, addition training under gone, duration, dates etc.

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