Implementation of Entity Relationships

1
Implementation ofEntity Relationships

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

2
Implementation ofEntity 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)
• 2 tables required
• Primary Key Strong Entity as Foreign Key
• FK can be null
• Eg. Patient has disease
• Implement in Access!

3
Implementation ofEntity 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)
• 2 tables required
• Primary Key of 1 as Foreign Key of M
• Eg. Doctor / Equipment
• Implement in Access!

4
Implementation ofEntity 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)
• 2 tables required
• Primary Key of 1 as Foreign Key of M
• FK can be null
• Eg. Hospitals / Equipment Distributors
• Implement in Access!

5
Implementation ofEntity 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