MODERN DATABASE MGMT.(PEARSON CHANNEL)
MODERN DATABASE MGMT.(PEARSON CHANNEL)
13th Edition
ISBN: 9780136709299
Author: Hoffer
Publisher: PEARSON
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Chapter 1, Problem 1.45PAE

Consider the project data model shown in Figure 1-16

  1. Create a textual description of the diagrammatic representation shown in the figure. Ensure that the description captures the rules/constraints conveyed by the model.
  2. In arriving at the requirements document, what aspect of the diagram did you find was the most difficult to describe? Which parts of the requirements do you still consider to be a little ambiguous? In your opinion, what is the underlying reason for this ambiguity?

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Consider the following relations:     Student(snum: integer, sname: string, rmajor: string,          level: string, age: integer)   Class(cname: string, meets_at: time, room: string, fid: integer)   Enrolled(snum: integer, cname: string)   Faculty(fid: integer, fname: string, deptid: integer)     The meaning of these relations is straightforward; for example, Enrolled has one record per student-class pair such that the student is enrolled in the class.     2. Express each of the following integrity constraints in SQL unless it is implied by the primary and foreign key constraint; if so, explain how it is implied. If the constraint cannot be expressed in SQL, say so. For each constraint, state what operations (inserts, deletes, and updates on specific relations) must be monitored to enforce the constraint.   (a) Every faculty member must teach at least two courses. (b) Every student must be enrolled in the course called 'Math101'. (c) A student cannot add more than two courses at a time…
Consider the following relational schema. An employee can work in more than one department; the pct_time field of the Works relation shows the percentage of time that a given employee works in a given department.   Emp(eid: integer, ename: string, age: integer, salary: real)  Works(eid: integer, did: integer, pct_time: integer)  Dept(did: integer, budget: real, managerid: integer)      Write the following queries in SQL:   a. Print the name of each employee whose salary exceeds the budget of all of the departments that he or she works in. b. Find the enames of managers who manage only departments with budgets larger than $1 million, but at least one department with budget less than $5 million.
Consider the following schema: Suppliers(sid: integer, sname: string, address: string)  Parts(pid: integer, pname: string, color: string)  Catalog(sid: integer, pid: integer, cost: real)  The Catalog relation lists the prices charged for parts by suppliers. Write the following queries in SQL:   a. Find the sids of suppliers who charge more for some part than the average cost of that part (averaged over all the suppliers who supply that part). b. Find the sids of suppliers who supply a red part or a green part. c. For every supplier that supplies a green part and a red part, print the name and price of the most expensive part that she supplies.
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