I need to draw a single Entity Relationship Diagram (ERD) to represent the following situation, which is described by means of text and a relational data model.


Situation
A relational database has been designed for a company which sells merchandise through magazine advertising. Customers who want to place an order call a toll-free telephone number and place an order for the items that they require. This order is entered through an on-line terminal and is later filled and shipped by the stock room. The customer may pay for the purchase by credit card or pay ‘collect’ (that is, they pay at the time the goods are delivered).
Each table is described below, with the primary key underlined and foreign keys defined.


Table structure:

CUSTOMER
customer_number (PK)
name
address
phone_number
credit_rating

ORDER
order_no (PK)
customer_number (FK)
order_date
shipping_address
credit_card_type
credit_card_number
foreign key (customer_number) references Customer


ITEM
stock_no (PK)
description
weight
colour
unit_price

ORDERED_ITEM
order_no (PK)
stock_no (FK)
quanity_required
unit_price
foreign key (order_no) references Order
foreign key (stock_no) references item

MAGAZINE
magazine_code (PK)
name
address
phone_number

EDITION
magazine_code (PK, FK)
issue_date
foreign key (magazine_code) references magazine

ADVERTISED_ITEM
magazine_code (PK, FK)
issue_date (FK)
stock_no (FK)
page_no
advertised_price
foreign key (stock_no) references Item
foreign key (Magazine_code, Issue_date) references Edition

when is it due, how much of it have you done so far, can we see it, and what's your question?

How do you start a diagram, do you follow the flow of the primary and foreign keys? How do you represent the relationships? I read that they should be expressed as verbs, why can't the primary keys be used in the diagram?

by using boxes to represent entities

they don't actually "flow"

usually with lines connecting related boxes

yes, that's a good idea, and remember to have two verbs, one for each direction

but they can

How would the flow be illustrated with the sample table data? Can you give me a sample on how this would flow?

Based on the database structure, is this the correct flow?
tables in capitals and relationships in lower case

CUSTOMER
places
ORDER
for
ORDERED_ITEM
from
ITEM
get
ADVERTISED_ITEM
from
EDITION
advertised
MAGAZINE

Thanks, but I'm still confused how to use the relationships and how to name them, can you help?