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OO class modelling 1
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OO class modelling 2
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Data/ Attribute Normalisation
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DFDs and STDs 1
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DFDs and STDs 2
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Answer all parts
of this question.
a. Explain why
it is important that the quality of a data design is checked before it is
implemented.
(3 marks)
b.
Give a definition of functional dependency
(3 marks)
c.
Draw a set of functional dependencies for the following case study.
(5 marks)
A nationwide supplier of electrical goods maintains a relational database
called SHOP.
The database contains a variety of information concerning the
company’s shops, their location and the products they have available within
each shops. A standard product
coding scheme is used across all shops.
The database shows how many products are available for sale in each
shop, together with the sale price of the product in each shop. Because of
different levels of competition around each shop’s location, managers have
discretion to sell products at different prices in their shop. The
manufacturer of each product is also shown, together with warranty offered by
the manufacturer. A warranty is the period in which the manufacturer will
replace the item free of charge if it fails during the warranty period.
For the products shown, the manufacturers have the same warranty
period for all their products.
Definition of the SHOP relation:
SHOP (shop-id,
shop-town, (product-id, product-name, manufacturer, warranty, quantity,
sale-price))
Sample data for the SHOP relation:
|
Shop Id
|
Shop Town
|
Prod. Id
|
Product
Name
|
Manufac-turer
|
Warranty
(months)
|
Qty
|
Sale Price
£
|
|
A5
|
Croydon
|
X257
G777
A515
|
Camcorder
Washing
machine
Ice cream
maker
|
Suzuki
Hotolux
Whip-o-cream
|
24
12
12
|
6
2
4
|
450
429
55
|
|
A17
|
Harrow
|
C339
A515
B880
|
Freezer
Ice cream
maker
VCR
|
Chillman
Whip-o-cream
Suzuki
|
18
12
24
|
1
3
2
|
175
50
275
|
|
M7
|
Chorlton
|
X257
A515
|
Camcorder
Ice cream
maker
|
Suzuki
Whip-o-cream
|
24
12
|
1
2
|
495
55
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d. Convert
the SHOP relation into first normal form, second normal form and third normal
form. You must show each normal
form, although if an entity is the same, you only need to state this and not
show the entity definition in full.
State any assumptions you make when normalising the relation.
(9 marks)
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