1. Implementation of Entity Relationships
1-1 Relationship (both mandatory)
1 table required – attribute of main table
Eg. Doctor has one specialty
2 tables required – foreign key in table
Eg. Doctor has one assigned nurse
Implement in Access!
Lab 4

2. Implementation of Entity Relationships
1-1 Relationship (one mandatory)
2 tables required
Primary Key of Mandatory as Foreign Key of Optional
Eg. Nurse / Office (1 nurse in an office)
1-1 Relationship (both optional)
Primary Key “Strong” Entity as Foreign Key
FK can be null
Eg. Patient has disease
Implement in Access!
Lab 4

3. Implementation of Entity Relationships
1-M Relationship (both mandatory)
2 tables required
Primary Key of 1 as Foreign Key of M
Eg. Doctor / Patient (1 doctor has many patients –no vice/versa)
1-M Relationship (1 mandatory M optional)
Eg. Doctor / Equipment
Implement in Access!
Lab 4

4. Implementation of Entity Relationships
1-M Relationship (1 optional M mandatory)
2 tables required
Primary Key of 1 as Foreign Key of M
Eg. Hospital Fire Marshall / Doctors
1-M Relationship (Both Optional)
FK can be null
Eg. Hospitals / Equipment Distributors
Implement in Access!
Lab 4

5. Implementation of Entity Relationships
M-N Relationships
3 tables required
2 tables contain primary key and attributes of entities
1 table contains primary key of 2 entities as foreign keys and other attributes
Eg. Patient / Medication
Lab 4