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• Data Value: Data Value is the value in the form of a text, number, date, audio, video, picture, etc. It is the smallest unit
of a database and is formed by the intersection of a row and a column. Vertically it is a part of a column and makes
a collection of similar data. Horizontally it is a part of a row and represents one complete information of a student
Let us take the example of student table as shown below:
Student
Rollno Name Date of Birth Address PhoneNo
11 Amaira 12/04/2007 Rohini 11223344
21 Shubham 01/03/2007 Kailash Colony 23234455
Table 12 Smith 21/09/2006 Pitampura 34344455
Records
33 Tisha 15/08/2006 Rohini 66778899
17 Smith 20/05/2007 Defence Colony 11227788
35 Tvesha 12/04/2007 Greater Kailash 44556677
In the above table there are 6 rows and 5 columns. If a new student joins a school then the complete information of
a new student will be added in the form of a record/row. The columns like Rollno will store only integers, Name will
store only text and Date of Birth will store only Date.
RELATIONAL DATABASE MANAGEMENT SYSTEM (RDBMS)
RDBMS is the next advanced form of Database Management System and is based on a Relational Model. In this model
a relational database has a set of related tables that are interlinked to each other on the basis of a common field. It
is a very efficient way of representing data and allows data in a table is represented in a two dimensional form and
is known as a Relation. A row that forms complete information is known as a Tuple. Each tuple uniquely identifies a
record on the basis of a unique key- Primary key. Data from different relations can be easily extracted as they are
interlinked on the basis of a Primary key. A column that stores similar data is known as an Attribute or a Key.
Domain
Columns or Fields or Attributes 5000,100000
Primary EMP_ID NAME POSTS Salary
Key
E1 Rahul Clerk 30000
Rows E2 Kapil Manager 90000
Records Cardinality (No. of Rows) = 4
or Tuples E3 Manoj Clerk 90000
E4 Mukesh Peon 20000
Degree (No. of Columns) = 4 Data Value
The concept of relational database was developed by E.F. Codd at IBM in 1970.
Database Management System 265

