Types of relationships

Types of relationships

1. One to one

   • One record that corresponds to another record in another tables
   • Inefficient
   • Example
     • Patient to treatment

2. One to many

   • One record that can be linked to many other records in another table

3. Many to many

   • Hard to implement
   • Many records that can be linked to many other records in another table

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

5. Relationships built up through stored 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