Transcript ERD – Expenditure Cycle

Entity Relationship
Diagrams (ERDs)
Entity Relationship
Diagram (ERD)


documentation technique to represent
relationship between entities in system.
Think of entities as “nouns” – nouns on
which a company would want to track
information. A few examples:




2
Vehicles
Accounts Receivable
Customers
Vendors
Entity Relationship
Diagram (ERD)
Think of the relationship as a “verb”
 The verb connects (relates) one entity
to another. A few examples:

Receive
 Assign
 Prepare
 Send

3
Cardinality between entities

represents the
numerical mapping
between entities:



one-to-one
one-to-many
many-to-many
4
Entity
Car
Relationship
1
is assigned
Customer
Company A
Entity
1
Salesperson
Entity
Relationship
1
Car
Entity
M
is assigned
Salesperson
Company B
Customer
Entity
Relationship
1
Customer
places
Entity
M
Order
This cardinality is probably true for most businesses.
7
Entity
Vendor
Relationship
M
supplies
Entity
M
Inventory
This cardinality would depend on the business.
8
ERD – Expenditure
Cycle
Describe the business rules
represented by the cardinalities
in the ERD.
1
VENDOR
1
M
M
M
P.O.
M
INVENTORY
1
M
M
1
REC. RPT.
10
Add 3 attributes for each entity.
1
VENDOR
1
M
M
M
P.O.
M
INVENTORY
1
M
M
1
REC. RPT.
11
3 attributes for each entity.
VENDOR
1
M
1
M
M
P.O.
M
INVENTORY
1
M
M
1
REC. RPT.
12
Modify the ERD, based on the
following information:
1
VENDOR
1
M
M
M
P.O.
M
INVENTORY
1
M
M
1
REC. RPT.
13
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
VENDOR
1
M
M
M
P.O.
M
INVENTORY
1
M
M
1
REC. RPT.
14
Add 3 attributes for each
new entity.
1
VENDOR
1
M
M
M
P.O.
M
INVENTORY
1
M
M
1
REC. RPT.
15
16