Tuesday, August 27, 2013

ER diagrams and discussion


The ‘Bookworm’bookstore has expanded recently and due to the dropping of price control on books now expects further rapid developments. To assist the company Buyer to keep track of the stock in the store, you have been employed to produce an initial model of the system.
The book shop sells both fiction and non-fiction books.
Books have an ISBN, bar-code, title, author(s) / editor(s), publisher, date of publication, quantity in stock, price, quantity on order.
For certain journals there mayalso be a series title.
Fiction books are either paperback, large paperback or hardback and may be ranked in the best seller list.
Non-fiction books belong to a subject area and may have an edition number.
Due to the expansion the shop now also sells other merchandise such as:
• magazines which have a bar-code, title, and issue number and/or date, publisher, price, quantity in stock, quantity on order.
• stationery items with bar code, price, quantity in stock, quantity on order, description, supplier.
• greetings cards with bar-code, price, type, quantity in stock, quantity on order, printer, description, supplier.
• seasonal items with bar-code, price, quantity in stock, quantity on order, supplier, start date, end date,description.
Customers make purchases for which they receive receipts having a receipt number, date, quantity, bar-code, brief description, price and sales person code.
Sometimes a special offer voucher may be offered in payment. These will have a voucher number, value, company of issue and expiry date.
The issue of a receipt causes the quantity in stock to be updated.
The sales person code is used to calculate the monthly bonus.
Although you have been asked to look at this from the Bookshop Buyer’s point of view your model will also include the bookshop sales area.
Tasks:
1. Produce an Entity Relationship diagram
2. Produce a use case diagram and class diagram for the system.
3. Explain how the subclass/superclass relationships and the type of specialisation involved in each were developed with reference to any alternatives considered
4. Explainhow Christmas and Easter cards can be handled by your model
5. Specify the Tables which you would propose to implement. Also explain how you might implement the specialisation hierarchy.
Task 2:
You are to reflect on the work done in the design assignment for this module (either the main case study or the referral case study), and consider how the tools you have used can contribute to a correct Database Design. The emphasis here is on the ER, and Use Case Models, although you are not limited to these.
The objective is to provide a clear and concise analysis of the database design tools and methods used in the module and to assess the contribution they make to ensuring that a database design we produce will be correct.
consider carefully how we might measure this concept of correctness.

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