Databases Reference
In-Depth Information
8. What is a star schema? What are fact tables? What
are dimension tables?
9. What is a snowflake feature in a star schema?
10. After a data warehouse is designed, what are the
four steps in building it?
11. Name and describe three possible problems in trans-
actional data that would require ''data cleaning''
before the data can be used in a data warehouse.
12. Name and describe three kinds of data transforma-
tions that might be necessary as transactional data is
integrated and copied into a data warehouse.
13. What is online analytic processing (OLAP?) What
does OLAP have to do with data warehouses?
14. What do the following OLAP terms mean?
a. Drill-down.
b. Slice.
c. Pivot or rotation.
15. What is data mining? What does data mining have
to do with data warehouses?
16. Describe the ideal background for an employee who
is going to manage the data warehouse.
17. Describe the challenges involved in satisfying a data
warehouse's user community.
EXERCISES
1. Video Centers of Europe, Ltd. data warehouse:
a. Design a multidimensional database using a star
schema for a data warehouse for the Video
Centers of Europe, Ltd. business environment
described in the diagram associated with Exercise
2.2. The subject will be ''rental,'' which repre-
sents a particular tape or DVD being rented by
a particular customer. As stated in Exercise 2.2,
be sure to keep track of the rental date and the
price paid. Include a snowflake feature based on
the actor, movie, and tape/DVD entities.
b. Describe three OLAP uses of this data ware-
house.
c. Describe
AIRPORT Table
Airport
Year
Name
City
State
Size
Opened
SKILL Table
Skill
Skill
Skill
Number
Name
Category
one
data
mining
use
of
this
data
warehouse.
2. Best Airlines, Inc., data warehouse:
In the exercises in Chapter 8, we saw the following
relational database, which Best Airlines uses to keep
track of its mechanics, their skills, and their airport
locations. Mechanic number, airport name, and skill
number are all unique fields. Size is an airport's size
in acres. Skill Category is a skill's category, such
as an engine skill, wing skill, tire skill, etc. Year
Qualified is the year that a mechanic first qualified
in a particular skill; Proficiency Rating is the
mechanic's proficiency rating in a particular skill.
QUALIFICATION Table
Mechanic
Skill
Year
Proficiency
−−−−−−
−−−
Number
Number
Qualified
Rating
−−−−−
−−−−−
We now add the following tables to the database
that record data about airplanes and maintenance
performed
on them. A maintenance
event
is a
specific
maintenance
activity
performed
on
an
airplane.
AIRPLANE Table
MECHANIC Table
Airplane
Airplane
Year
Passenger
Mechanic
Mechanic
Airport
Number
Model
Manufactured
Capacity
−−−−
Number
Name
Telephone
Salary
Name
−−−−
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