This exam consist of 3 parts. This is Part 1. Write your answer in one pdf or docx format or type them here.
I. Assuming the schema for a database,
employee (employee-name, street, city)
works (employee-name, company-name, salary)
company (company-name, city)
manages (employee-name, manager-name)give SQL queries for the following questions, assuming a person can have more than one job and a company can exists in more than one city:
1) A list of the names of those employees who work for the Google.
2) A list of the names and cities of residence for those employees who work for Google.
3) A list of the names, streets and cities of residence for those employees who work for Google and earn more than $250000 a year.
4) A list of the names of those employees who live in the same city as the company for which they work.
5) A list of the names of those employees who live in the same city and on the same street as their managers.
6) A list of the names of those employees who do not work for Google.
7) A create statement for the table works, including the keys.
part 2
This exam consist of 3 parts. This is the 2nd part Write your answer in one pdf or docx format.
II. Write a 1200-2000 words essay about the attribute closure algorithm studied in slides, reproducing the algorithm and describing it line by line with its logic and applications to the detection of candidate keys. The essay should contain the following sections:
a) Motivation
b) The algorithm reproduced from slides
c) A line by line description of its logic and complexity
d) Exemplify computing the attribute closure (C,D)+ for the following problem:
R=(A,B,C,D,E)
F={B->A; C->A; DE->AC; E->B }
e) Exemplify the process of finding and proving a candidate key for the problem at (d)
f) Describe applications of the algorithm to other problems
part 3
This exam consist of 3 parts, this being the 3rd part, and is personalized. Write your answer in one pdf or docx format.
III. Write a 1000 word essay, reproducing the corresponding algorithm or definition and describing it line by line with its logic and applications, for the following personalized topic (find the topic associated with your name).
A. Alfifi Functional Dependencies closure