Database案例CS专业数据库Task1.2.3.4
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2019-04-27

Task 1
The database for Pulse Learning is modelled in Figure 1. The diagram is based on the information provided by Pulse Learning.



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Task 2

The relational model of X database is modelled below. The model is derived from the use case and the ERD in Figure Deriving Entity types

RELATION (attribute, attribute, attribute)

RELATION (attribute, attribute, attribute)

Deriving Relationship types
RELATIONSHIP NAME was derived by adding RELATION with attribute and attribute as foreign keys to link with RELATION and RELATION because of MULTIPLICITY and/or PARENT/CHILD

RELATIONSHIP NAME was derived by merging RELATION and RELATION because of MULTIPLICITY and/or PARENT/CHILD

RELATIONSHIP NAME was derived by adding attribute to RELATION as a foreign key to link with RELATION because of MULTIPLICITY and/or PARENT/CHILD

Relational Model
RELATION (attribute, attribute, attribute)

RELATION (attribute, attribute, attribute)

RELATION (attribute, attribute, attribute)

RELATION (attribute, attribute, attribute)

RELATION (attribute, attribute, attribute)


Foreign Keys
· Relation (attribute) is dependent on Relation (attribute).

· Relation (attribute) is dependent on Relation (attribute).

Other Constraints
· The X attribute of the Y relation can only be from 1000 to 9999.

Task 3


Relation

Attribute

Attribute

Attribute

Attribute

Attribute

value

value

Value

Value

Value

Value

Value

Value

value

Value

Value

Value

value

Value

Value

value

Value

value

value

value





· A delete operation that would run successfully

Delete the row:

value

Value

value

value

value

From Relation


· An update operation that would run successfully

Update the row:

value

Value

value

value

value

From Relation to

value

Value

value

value

value


· An update operation that would not run successfully

Update the row:

value

Value

value

value

value

From Relation to

value

Value

value

value

value



· An insert operation that would not run successfully

Insert the row:

value

Value

value

value

value

Into Relation




Task 4

Student is xNF because it respects A and B but there is Z which prevents it from being (x+1)NF

Tutor is xNF because it respects C and D but there is W which prevents it from being (x+1)NF

Coordinator is xNF because it respects E and F but there is Y which prevents it from being (x+1)NF





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