6.2 Anomalies in Relational Database Design | insertion anomaly | deletion & Updation anomaly

PLAYLIST:
DBMS Data Base Management System Tutorials In Hindi | GATE NET DBMS Lectures in Hindi
   • DBMS Complete Syllabus All Universit...  

Relational Database Design Functional Dependencies And Normalization
   • DBMS Relational Database Design & Fu...  

dbms tutorials,
database management system tutorial,
database tutorials,
relational database design,
dbms lectures,

dbms gate lectures in hindi,
ugc net dbms tutorials in hindi,
gate dbms tutorials,
ugc net dbms tutorials,

#gatedbmslecturesinhindi
#ugcnetdbmslecturesinhindi
#gatedbmslectures
#ugcnetdbmslectures
#dbmsLectures
#dbmsTutorials

There are various anomalies or pitfalls in a relational database. Various dependencies in relational. database cause these anomalies.
Anomalies: Anomalies refer to undesirable results because of the modification of data.
Consider the relation Employee with attributes EID, Name, Salary, Dept.No, Dept. Name The various anomalies are as follows:

Insertion Anomaly
Suppose you want to add new information in any relation but cannot enter that data
because of some constraints. This is known as an Insertion anomaly. In relation Employees, you
cannot add a new department to Finance unless there is an employee in the Finance department.
The addition of this information violates Entity Integrity Rule 1. (Primary Key cannot be NULL).
In other words, when you depend on any other information to add new information then
it leads to an insertion anomaly.
2. Deletion Anomaly
The deletion anomaly occurs when you try to delete any existing information from any
relation and this causes deletion of any other undesirable information.
In relation Employee, if you try to delete tuple containg Deepak this leads to the deletion
of department “Sales” completely (there is only one employee in sales department).
3. Updation Anomaly
The updation anomaly occurs when you try to update any existing information in any
relation and this causes inconsistency of data.
In relation Employee, if you change the Dept.No. of department Accounts.
We can update only one tuple at a time.
This will cause inconsistency if you update Dept.No. of single employee only otherwise you
have to search all employees working in Accounts department and update them individually. Notes Link:
http://www.tutorialsspace.com/Downloa...