A database of documents, authors, and readers.

Write Relational Query Expression to do the following:

a. Find all the committee names where instructor Abdullah is a member

b. Find the maximum given salary.

c. Find the total number of instructors for each department.

Question Two
Consider the following relation instances:

Student

Student_id Name Course_code
10001 Abdullah IT244
10002 Mohammed CS140
10003 Nasser CS141
10004 Khalid IT403

                             Course

Course_code
Course_name
IT244 Introduction to databases
CS140 JAVA I
CS141 JAVA II
CS566 Cyber Security

Write the output of the following relational algebra expression:

a. Student Course

 b. Student           Course

Question Three
You have been asked to design a database of documents, authors, and readers. described as follows:
• Document: has a docID, title
• Publisher: each author is the creator of several documents, and each document is published by one or several publishers.
• Readers: each reader reads several documents, and each document is read by several readers.
Draw an E/R diagram, which includes entity, attributes, and relationships. Remember to indicate the key for each entity, as well as the multiplicity of each relationship using the appropriate notation.(You may presume your own scenario)

Sample Solution

ACED ESSAYS