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Relational Database

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Submitted By ngozialex55
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Relational Database- Semester 2
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Assignment 1 Due date: 5 August 2014

Question 1 a. Why are tuples in a relation not ordered? b. Why are duplicate tuples not allowed in a relation? c. What is different between a key and a superkey d. Why do we designate one of candidate keys of a relation to be the primary key? e. Discuss the characteristics of relations that make them different from ordinary tables and files. f. Discuss the various reasons that lead to the occurrence of NULL values in relations g. Discuss the entity integrity and referential constraints. Why is each considered important? h. Define foreign key. What is this concept used for? i. What is a transaction? How does it differ from an update operation [3 marks each]

Question 2

2.1 Specify the following queries in SQL on the database schema of figure 1 a. Retrieve the names of all senior students majority in CS (computer science). b. Retrieve the names of all courses taught by Professor King in 2013 and 2014 c. For each section taught by Professor King, retrieve the course number, semester, year, and number of students who took the section.

d. Retrieve the name and transcript of each senior student (class=4) majority in CS. A transcript includes course name, course number, credit hours, semester, year, and grade for each course completed by the student. [4 marks each]

2.2 Write SQL update statements to do the following on the database schema shown in figure 1 a. Insert a new student, <’Johnson’, 25,1,’math’> in the database b. Change the class of student ‘Smith’ to 2 c. Insert a new course, <’Knowledge Engineerig’,’ÇS4390’,3,ÇS’> d. Delete the record for the student whose name is ‘Smith’ and whose student number is 17. [3 marks each]

No late assignments will be accepted!!!!

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