What is Relational Data base management system(RDBMS) ? Discuss about Relational Data base management system(RDBMS) with suitable example
Relational Data Base Management System (RDBMS) :-
The relational model represent the data base as a collection of relation. Generally each relation is represented by a table of values. For exam. The data base of files given below is considered to be in the relational model.
Tab-1
STUDENT | NAME | STUDENT NUMBER | MAJOR |
Milan Malay | 17 18 | CS CS |
Tab-2
COURSE | COURSE NAME | COURSE NUMBER | DEPARTMENT |
Data structure Database Discrete Math | CS 131 CS 380 CS 230 | CS MATH CS |
Tab-3
GRADE REPORT | STUDENT NUMBER | GRADE |
17 18 8 8 8 | B C A B A |
It may be noted that each of the above table is known as relation and the whole database is called relational database.
When a relation is presented as table of values, each row in the table represents a collection of related data values. In the above examples, the first table is called STUDENT because each row represents facts about a particular student entity.
In a formal relational model, a row is called a table. A column header is called an attribute and a table is called relation.
EXAMPLE :-
Student ----Roll
Name
Address
Super key = { Roll}
{ Roll, Name }
{ Roll, Name, Address }
{ Name, Address }
Candidate Key= { Roll }
{ Name, Address }
Primary Key = { Roll }
Alternate Key = { Name, Address }
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