What is many-to-many relationship in database?

Answer 1

An many-to-many relationship exists when an entity A can have a relationship with multiple entities B and vice versa.

Examples

An employee may learn many jobs skills, and each job skill may be learned by many employees. EMPLOYEE learns SKILL is M:N relationship.

One student may take many courses and one course is attended by many students.

An order can contain many products and a product can be contained in many orders.

Answer 2

There are three kinds of relations that can exist between two entities. These are one to one , one to many and many to many. In many to many entities relation n(A) entity can have relation with m(B) entity.