Types of relationships

Types of relationships

1. One to many

   • One record in one table can have many links to data in a different table, example: one customer may have many orders.

2. One to one

   • one record in one table is linked too another table.
     • inefficient
   • Patient will have one doctor, one appointment

3. Many to many

   • More than one thing can be linked to another table
   • Many videos to many customers for example

4. Relationship

   • Information in stored in sets of related tables based on the entities
   • Overcome the problems of storing everything in single tables.
   • Relationships built through shared common fields

5. Entity relationship diagrams (EDRs)

   • An EDR is a specialised graphic that shows the relationships between entities in a database.