Sixth Chapter Lesson-8 Database Relationship and Database Relation.

In this lesson, you will learn-

  • 1. Database relationship and it’s  Degree.
  • 2. Database relation and it’s  classification.

 

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:

  1. There must have one common field between relational tables and data type, field size and format must be same for that common field.
  2. 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 –

  1. One to One
  2. One to Many
  3. Many to One
  4. 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- 

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