At the end of this lesson-
- 1. You will be able to explain database relation.
- 2. You will be able to describe the conditions of database relation.
- 3. You will be able to explain classification of database relation.
Database Relation: Relation between records of a table with the records of another table of a database is called database relation.
Condition for making database relation:
- There must have one common field between relational tables and data type, field size and format must be same for that common field.
- There must have a primary key field on at least one of the relational tables.
Types of database relation: There are four types of database relation. They are –
- One to One
- One to Many
- Many to One
- Many to Many
One to One Relation: If a record of a relational table is related to only one record of another relational table, the relation between them is called one to one relation.
One to Many Relation: If a record of a relational table is related to multiple records of another relational table, the relation between them is called one to many relation.
Many to One Relation: If multiple records of a relational table are related to one record of another relational table, the relation between them is called many to one relation.
Many to Many: If multiple records of a relational table are related to multiple records of another relational table, the relation between them is called many to many relation.
Lesson Evaluation-
Knowledge Based Questions:
- a.What is database relation?
- a. What is database relationship?
Comprehension Based Questions:
- b. Write down the conditions for making relation between two tables.
- b. ‘There is condition for making relation between two tables’ – explain.
Creative Questions:
Read the stem and answer the following question:
d. Which type of relation exists between above two tables? Analyze with argument.
Multiple Choice Questions:
Written by,
- Mizanur Rahman (Mizan)
- Lecturer of ICT, Shaheed Bir Uttam Lt. Anwar Girls’ College ,Dhaka Cantonment
- Author at www.edupointbd.com
- Software Engineer at mands IT
- Former Lecturer of ICT, Cambrian College, Dhaka
- Email: mizanjust@gmail.com
- Cell: 01724351470