1. Entity Relationship Diagrams (ERDs)

2. Entity Relationship Diagram (ERD)
documentation technique to represent relationship between entities in system. 21

3. Depends on business rules !!
Cardinality
represents the numerical mapping between entities:
one-to-one
one-to-many
many-to-many
Depends on business rules !! 22

4. Cardinalities 1 1 Entity Relationship Entity Sales- person Car
is assigned
Customer
Company A 23

5. Cardinalities 1 M Entity Relationship Entity Sales- person Car
is assigned
Company B
Customer 23

6. Cardinalities
Entity
Relationship
Entity 1 M
Customer
places
Order 23

7. Cardinalities M M Entity Relationship Entity Vendor Inventory supplies23

8. ERD – Expenditure Cycle

9. Describe the business rules represented by the cardinalities in the ERD.
VENDOR 1 1 M M
P.O. M
INVENTORY M 1 M M
REC. RPT. 1

10. Add 3 attributes for each entity.
VENDOR 1 1 M M
P.O. M
INVENTORY M 1 M M
REC. RPT. 1

11. 3 attributes for each entity.
VENDOR 1 M 1 M
P.O. M
INVENTORY M 1 M M
REC. RPT. 1

12. Modify the ERD, based on the following information:1
VENDOR
The Vendor sends an invoice for each shipment. The invoice is matched to the RR; a Cash Disbursement (CD) is prepared for each invoice. 1 M M M
P.O. M
INVENTORY 1 M M 1
REC. RPT. 12

13. VENDOR 1 1 M M
P.O. M
INVENTORY M 1 M M
REC. RPT. 1

14. Add 3 attributes for each new entity.
VENDOR 1 1 M M
P.O. M
INVENTORY M 1 M M
REC. RPT. 1

15. The End