Introduction to Relational Database
A Relational Database is a kind of database that stores, maintains and presents mutually related data points.
Let’s understand this using an example:
STUDENTS
| S.No | S. Name | Age | Qualification | D.O.B |
| 001 | Alex | 19 | Btech | 18-01-2002 |
| 004 | Max | 19 | Btech | 25-08-2002 |
| 007 | Glen | 20 | Btech | 23-04-2001 |
| 010 | Patrik | 20 | Btech | 02-07-2001 |
| 017 | Maggie | 20 | Btech | 13-06-2001 |
- Table: A relational database has a collection of ‘Tables’ where each one is assigned to a unique name.
Example: STUDENTS in the above table.
- Relation: ‘Relation’ is used to refer to a table.
- Tuple: A row in a table is referred to as a ‘Tuple’.
Example:
| 007 | Glen | 20 | Btech | 23-04-2001 |
- Attribute: A column in a table is referred to as an ‘Attribute’.
Example: ”S.Name”
- Domain: The set of all values in an attribute of a relation is called a ‘Domain’.
Example: [001, 04, 007, 010, 017]
- Atomic Domain: If the elements of a domain are considered to be indivisible, then they are called ‘atomic domains’.
Ex : [001, 04, 007, 010, 017]
Properties of Relational Database
- The name of the relation is unique from all other relations.
- Each relation cell contains only one atomic value.
- Each attribute contains a definite name.
- The attribute domain has no significance.
- tuple has no duplicate value.
- Order of tuples can have a unique sequence.
Reference :
Introduction to Relational DBMS.