Skip to main content

Relation model concept and its advantage & disadvantage - Computer science fundamentals tutorial

    Relation model concept and it's advantage & disadvantage

   PDF version of this post also available. to get the pdf click the link given at  the  end of this post.      
    
1.What is relational model?
  Ã˜ Relation model represent database as a collection of relations. A relation is nothing but a table of values. Every row in the table represents a collection of related data values. This row in the table denotes a real world entity or relationship.

     Relational model concept: -
  ·Attribute: -Each column in a table, Attributes is the properties which define a relation. Example: - DNO, DNAME.

  ·Table: - In the relational model relations are saved in the table format. A table has two properties rows, column. Rows represent records and column represents attributes.


  · Degree: - The total number of attribute which in the relation which called the degree of relation.

  ·Cardinality: -Total number of rows present in the table.

    Attribute domain: -Every attribute has some predefined values and scope which is known as attribute domain.

     Advantage of relational model: -
    1) Simplicity: - A relational data model is simpler than hierarchical model and network model.

    2) Easy to use: - The relational model is easy as table consisting of rows and column is quite natural and easy to understand.

    3) Data independence: - the structure of a database can be changed without having to change any application.

    4)   Query capability: -It make possible for a high level query language like SQL to avoid complex data navigation.

      Disadvantage of using relational model: -
   · Few relational databases have limits on field length which cannot be exceeded

   · Relational databases can sometime become complex as the amount of data grows and the relation between pieces of data become more complicated.     

     ·Complex relational database may lead isolated databases where information cannot be shared from one system to another. 
        
                        click here For PDF of this post           
    PDF of  Relation model concept and its advantage & disadvantage

  

Labels:

Comments

Post a Comment

please subscribe my blog and let me suggest how I improve this site

Popular posts from this blog

Important MCQ of RDBMS( Relational database management system)-FCST

Important MCQ of RDBMS  1. A RDBMS consists a collection of ? a. Tables b. Fields c. Records d. Keys  ANS/- a. table 2. The term attribute refers to a ___________ of a table a. Record b. Tuple c. Column d. Key   ans/- c. Column 3. In relational model, the row of table is known to be ?  a. Relation b. Entity field c. Tuple d. Attribute  ans/- C. Tuple 4. . Address field of a person should not be part of primary key, since it is likely to ? a. Dependent b. Too long c. Changed d. Not changed  ans/- c. Changed 5. The relational model is concerned with ? a. Data structure and Data integrity b. Data Manipulation c. Both a and b d. None of these  ans/- c. Both a and b 6. Which is the false statement from the following ? a. A veiw is a named derived table b. A name relation is variable c. A veiw is a named reation and is virtual d. None of these  ans/- d. None of these 7. The union of primary key...
6 comments
Read more

Short notes on database schema & database independence- computer science fundamentals tutorial

            Database Schema &  Data Independence PDF version of this post also available. to download the click the link given at the end of this post.           Database Schema : -  A database schema   is the skeleton structure that represents the logical view of the entire database. It defines how the data is organized and how relat ion among them are associated.  Database schema  formulates all the constrains that are to be applied on the data. A database schema defines its entities and the relationship among them. It contains descriptive details of the database which can be described by means of schema diagram. A database schema can be divided into two categories.   I.     Physical database schema : - this schema contain to the actual storage of data and its form of storage like files, indices etc. It defines how the data will be stored in a secondary storage. ...
2 comments
Read more

C program to find factorial of number using function - FCST

C program to find factorial of number using function Problem description In this program take number as input & then it show the factorial of given number as output. Problem solution 1.take a number as input. 2.declare the void Fact(int) function globally if you want or declare the function prototype  into the main() function. 3.after taking input call the function into main() . 4.then define the function definition. 5.after taking function definition for loop started in this function definition. 6. In for loop i=1 & fact=1 then fact=1. after this loop is continue and incremented by1 until the n is grater than equal to i. continuity of loop is depend on what number take as input .  Program code: #include<stdio.h> void Fact(int);//function prototype declearation int i,fact=1;//global variable declearation int main()  { int n; printf("\n enter the  number:"); scanf("%d",&n); Fact(n);//function call } //func...
Post a Comment
Read more