| Help me please!!! [message #201982] |
Tue, 07 November 2006 13:17  |
blablabla
Messages: 1
Registered: November 2006
Location: Malaysia
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Junior Member |
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HeLLo...
aLL frenz
I'm taking database subject
but I'm realli weak on it
I got task to do
but find difficulty in it
I hope got somebody can help me!!!
Here are the questions :
ABCTrain
ABCTrain is a private education provider (PEO) offering a wide range of short courses. The courses offered are either language training courses or IT training courses. Students enrolled into the courses are assigned to different classes. Each class is identified by a class code. Other details of a class include the date for the start (SOC) and the end (EOC) of the class, and the daily schedule of the class. The daily schedule shows the classroom, and the time for each lesson. Each course is identified by a course number. Details of the course include the course title, course description, and the course fee. ABCTrain hires some full time instructors. It also maintains a list of part time instructors. Full time instructors are employees of the organization and thus are identified by the employee IDs. Only one instructor, full time or part time, is assigned to a class. Each instructor is associated with a list of courses that the instructor is capable of teaching. Part time instructors are assigned to the classes on contracts.
As the business is expanding, the number of Sales, Operation, and Instructor employees grow. As a consequence, there are many meetings within ABCTrain. Any employee may call for a meeting by inviting other employees for the discussion on a certain issue. Other details of the meeting include the title, the agenda, the chairperson, and the status. Each discussion of the meeting is recorded in a minute. The minute is available after the meeting is over. The minute taker is selected from one of the invitees of the meeting.
Answer all the following questions. State clearly any assumptions you made.
Question 1:
In the design of a database, the first step is drawing the conceptual model (EER diagram).
With reference to the case study given above, perform the following tasks:
a)Identify all the real world entities giving a candidate key and suitable attributes for each entity.
b)Identify an entity with a composite attribute.
c)Identify an entity with a multi-valued attribute.
d)Identify a weak entity present in the case study and determine its relationship with the owner entity.
e)Identify any one relationship with cardinality ratio 1: M.
f)Identify any one relationship with cardinality ratio N: M.
g)Identify two sets of Super/subtype entities
h)Identify any one possible ternary relationship in the given scenario.
i)Give an example from the above scenario of the additional semantic feature of relationships with
•Total participation,
•Partial participation.
j)Draw a complete EER diagram.
Question 2:
Use the algorithm from Elmasri and Navatheas a guide, convert the EER model to a relational model. You should show your working, step by step through the algorithm.
Question 3:
a)Identify all functional dependencies available in the above scenario.
b)Based on the dependencies identified in (a), produce a set of Boyce-Codd Normal Form relations.
Question 4:
Compare and contrast the Entity driven approach (Question 2) and the Dependency driven approach (Question 3) for logical database design. Your answer should include the guidelines for the database designer to decide when to use what approach and how. In particular, for the given case study, and with the given information, decide which is the better approach for logical database design.
Question 5:
Here are some of the transactions, which will be run against the database. Write the
relational algebra expressions for given transactions. Clearly specify the relational schema that you would be basing your answer on, i.e, Question 2 or Question 3.
Assumption: Tom is a fulltime instructor in ABCTrain
i)Show all the courses taught by Tom.
ii)Show all the students taught by Tom.
iii)Show the names of the part time instructors who have not taught any classes yet.
iv)Show the names of the fulltime instructors who have taught all the courses available.
v)List the titles and the dates for the meetings for which Tom has been selected as the minute taker.
I hope anyone can help me...
Thz b4
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