Types of Relationships

Types of Relationships

1. One-to-One

   • 1 record in 1 table is linked to only 1 bit of information in another table.
   • EG: A patients information will get sent to 1 doctor.

2. One-to-Many

   • 1 record is linked to another table with many pieces of information.
   • EG: A customer renting / buying many video tapes.

3. Many-to-Many

   • More than 1 thing which is linked to one table can be linked to another.
   • EG: Different videos sent to many people.

4. Information is stored in sets of related tables based on the entities.

5. Relationships built through shared common fields

6. Overcome the problems of storing everything in single tables.

7. An entity relationship diagram (ERD) is a specialised graphic that shows the relationships between entities in a database.