What is Relational Model?
The Relational Model was proposed by E.F. Codd in 1970. It organizes data into tables called relations. Each table contains rows and columns that store related data.
Basic Terminology
- Relation → Table
- Tuple → Row
- Attribute → Column
- Domain → Set of valid values
- Degree → Number of attributes
- Cardinality → Number of rows
Example of Relation
Student Table
- Roll No
- Name
- Branch
- Marks
Keys in Relational Model
- Primary Key
- Candidate Key
- Super Key
- Foreign Key
- Alternate Key
- Composite Key
Primary Key
A Primary Key uniquely identifies each record in a table. No two rows can have the same primary key value.
Foreign Key
A Foreign Key is used to establish a relationship between two tables. It refers to the primary key of another table.
Advantages of Relational Model
- Simple structure
- Easy data retrieval
- Reduces redundancy
- Supports data integrity
- Flexible database design
Exam Points
- E.F. Codd introduced Relational Model in 1970.
- Relation = Table
- Tuple = Row
- Attribute = Column
- Primary Key uniquely identifies records.
- Foreign Key creates relationships.