18-01-2006

Oracle is RDBMS. RDBMS stands for Relational Data Base Management System. It was proposed by Dr. Edgar F. Codd. This database system was not widely accepted because majority of population at that time consisted of people belonging to commerce and accounts. Its obvious that all applications and softwares were also made for their use. How ever RDBMS required usage of set theory which is branch of Mathematics and Arithmetics. This was not easily digestible to them. Hence it faced lot of opposition.


Update Anomaly. (If we have to update particular entity and in case that entity is present at no of places then there are chances that we may forget to change that entity at some place. )

Deletion Anomaly. ( If we delete some data the other data should remain intact. Take for example that if particular student has completed his course and hence leaving the institute then his account needs to be get deleted. But in that case other entities like Subject detail, Fees detail, Duration and phone no etc will also get deleted.)

Insertion Anomaly. (Using this method of storing data we can store data for only the items which we have presently in our hand. Suppose a new course is started then it is not possible to make its entry.)


Transitive Dependencies:
When non primary key attributes depends on other non primary key attributes which in turn depends on some primary key attributes then it is called Transitive Dependencies.

Concept of Relational:
The meaning of the term relational is when the data is stored in the tables are related to each other through a common column as well as in each table all the attributes are related to each other by way the common functional dependencies on the primary key. The relation between the two tables typically represent the natural relation between the two entities. In the real world, entities are never isolated but they are always related to each other.