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Brief About Database Management System (PART - 1)

DBMS 


  • What is a Database?

     Database is a collection of related data. It is a collection of Schema, tables, quarries, reports, views and other objects.


  • Who use Databases?

     Libraries , Banks , Military , Airlines , Supermarkets.etc


  • What is DBMS?


     DBMS is a computer software that use to access data in database or interact with user.
General purpose of designing DBMS is create and maintain the database.(definition, querying, update and administration)


  • What are the basic steps to design DBMS?


     1.Requirement Analysis
          It is the process that determine what user want.

     2.Conceptual Design
          The main purpose of conceptual design is create ER-Model. It describe how different entities related to each other.(It also describe what attributes each entity has.)

     3.Logical Design
          Transfer ER-Model into relational schema.

     4.Normalization / Schema Refinement
          The goal of Normalization is eliminate redundancy (redundancy means same data is saved more than one time in the database - Duplicate data) 

     5.Physical Designing
          Implement the database.(make database work.)

     6.Security Designing
          Ensure security of database.
  

Useful things in DBMS


  • Entity
An entity is a real-world object. It should be easily identifiable.
        Ex - In a School Database
                   Students
                   Teachers
                   Classes 
  • Entity Set
Entity set means set of entities that have same type of data.
        Ex - All persons having account at a bank

  • Attributes and Domain of an Attribute
The property that describe the ENTITY called attributes.

Lets take a Example, Here is the Small Database of a school
                                                           STUDENTS
NO Student Age
S1 Sadun 12
S2 Naveen 15

So, using this example table we can identify followings,
                    Attributes - NO , Student , Age

Domain is a set of permitted values.

     EX - Name -------- A-Z , a-z  
              AGE  -------- 0 - 15

    This mean we only allow NAME attribute for A-Z letters and a - z letters. you can't type any other things in this field. Also in the AGE field, we can put only student who are in age 0 - 15. We can't add age 16 students here. Those are the permitted values.

  • Composite Attributes
The composite attributes means attributes that can subdivided into parts.

    Ex - Lets take a field name Stu_Name. This field can be subdivided into Stu_FirstName , Stu_LastName , Stu_MiddleName. so Stu_Name is a Composite Attribute.



ARTICLE BY - NISAL PRIYANKA
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