Reference no: EM13750528 , Length: 2137 words

Question 1. What is a relational database?

Write a 1500 word essay on the above question. Your response should include the evolution of 1st generation data models, the relevance of seminal work that led to the 2nd generation data model, a discussion of higher order semantics in the relational data model, and an explanation of the related concepts, theories, and modeling notations that are used to create the logical model of a relational database. Elaborate on the role of functional dependencies in normalization, and how the goal of eliminating insertion, deletion, and update anomalies is achieved in relational design. Describe relations in the context of the conceptual and logical data model, as well as the physical implementation of the relational database.

Question 2.

(a) Describe the major advantages and disadvantages of a database system approach to managing data.

(b) Given the DBLC as a structured methodology for designing and implementing a database system, explain the activities that are associated with each phase.

(c) Describe four significant differences between a file-processing system and a DBMS.

(d) Outline at least two reasons why database systems support data manipulation using a declarative query language such as SQL, rather than just providing a library of C or C++ functions to carry out data manipulation. Support your answer by example.

Question 3.

Part 1. Given the following employee database:

Employee (employee_ID, employee_name, street, city, zip, manager_ID)
Works (employee_ID, company_ID, hire_date, salary)
Company (company_ID, company_name, city)

Where the primary keys are underlined with a solid line and any foreign keys are underlined with a dashed line, give an expression in SQL for each of the following queries:

(a) Find the names and cities of residence of all employees who work for ABC Corporation.

(b) Find the names, street addresses, and cities of residence of all employees who work for ABC Corporation and earn more than $10,000.

(c) Find all employees in the database who do not work for ABC Corporation.

(d) Find all companies located in the city in which ABC Corporation is located.

(e) Find all employees hired on or after January 1, 2010. (Note: make sure to use a function on the date column to ensure the date formats in the condition statement match)

Part 2. The Oracle Instance and Transaction/Query Processing

(a) Illustrate and detail the architecture of the Oracle instance, including all memory structures, processes, and associated physical files.

(b) Explain how transactions are processed by the Oracle DBMS.

(c) Explain how queries are processed by the Oracle DBMS.

Question 4: Consider a database used to record the marks that students get on different examinations of different course offerings.

(a) Construct an E-R diagram for the database that models exams as entities, and uses a ternary relationship.

(b) Construct an alternative E-R diagram that uses only a binary relationship between students and course_offerings. Make sure that only one relationship exists between a particular student and course_offering pair, yet you can represent the marks that a student gets in different exams of a course offering.

(c) Design an E-R diagram for keeping track of the exploits of your favorite sports team. You should store the matches played, the scores in each match, the players in each match, and individual player statistics for each match. Summary statistics should be modeled as derived attributes.

(d) Construct an E-R diagram for a car insurance company whose customers own one or more cars each. Each car has associated with it zero to any number of recorded accidents.

(e) A weak entity set can always be made into a strong entity set by adding to its attributes the primary key attributes of its identifying entity set. Outline what sort of redundancy will result if we do so.