Consider the relational schema below: Students(sid: integer, sname: string, major: string) Courses(cid: string, cname: string) Enrollment(sid: integer, cid: string, grade: real) Write a tuple relational calculus expression that satisfies this query? Find the distinct names of all students who major in either "Math" or "Economics" who score less than 60% in either course 91.574 or in course 14.501 (using cid)

Consider the relational schema below: Students(sid: integer, sname: string, major: string) Courses(cid: string, cname: string) Enrollment(sid: integer, cid: string, grade: real) Write a tuple relational calculus expression that satisfies this query? Find the distinct names of all students who major in either "Math" or "Economics" who score less than 60% in either course 91.574 or in course 14.501 (using cid)

Database Systems: Design, Implementation, & Management

12th Edition

ISBN:9781305627482

Author:Carlos Coronel, Steven Morris

Publisher:Carlos Coronel, Steven Morris

Chapter8: Advanced Sql

Section: Chapter Questions

Problem 18RQ

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For the given schema, write relational algebra for the following queries. Student (id, name) EnrolledIn (id, code) Subject (code, lecturer) 1. What are the names of students enrolled in cs3020? 2. Who teaches cs1500 or cs3020? 3. What are the names of students in cs1500 or cs3010? 4. What are the names of students in both cs1500 and cs1200? 5. Which subjects is Hector taking?
Consider the relational schema below: Students(sid: integer, sname: string, degree: string, gpa: real) College(cid: integer, cname: string) Enrollment(sid: integer, cid: integer, onCoop: boolean) create a relational algebra expression that satisfies this query? Find the total number of all students in the Dep. Lutheran who have a GPA below 3.0 and are not interning. Submit your answer as one or more LaTeX expression in the answer field below.
Consider the following relational schema and answer the following questions. Employee (Employee_Id, First_Name, Last_Name, Email, Phone_Number, Hire_Date, Job_Id, Salary, Commission_Pct, Manager_Id, Department_Id) a. Write a query to find the manager ID and the salary of the lowest-paid employee for that manager. b. Write a query to get the department ID and the total salary payable in each department. c. Write a query to get the average salary for each job ID excluding programmer. d. Write a query to get the total salary, maximum, minimum, average salary of employees (job ID wise), for department ID 90 only.
TRUE OR FALSE In the Relational Data Model, Referential Integrity Constraint is a special kind/case of Foreign Key Constraint. Multiple Inheritance happens when a class has more than one sub-class. This problem can be observed in Programming Languages as well. Given two relations named A and B, if we q-JOIN A and B, the maximum number of attributes in the result relation could be (the number of attributes of A) times(*) the number of attributes of B). * in an SQL SELECT statement means “all the tuples”. In relational algebra, Cartesian Product (X) can be implemented using the q-JOIN operator. Cartesian Product ISA q-JOIN where q-condition always evaluates to true. SQL is based on Predicate Calculus. A query in SQL always specifies what should be included in the query result.
Consider the following SQL query on the university schema: select avg(salary)-(sum(salary) / count(*)) from instructorWe might expect that the result of this query is zero since the average of a set of numbers is defined to be the sum of the numbers divided by the number of numbers. Indeed this is true for the example instructor relation in Figure 2.1. However, there are other possible instances of that relation for which the result would not be zero. Give one such instance, and explain why the result would not be zero.
Consider the relational schema below: Students(sid: integer, sname: string, major: string) Courses(cid: integer, cname: string, hours: integer) Enrollment(sid: integer, cid: integer, grade: real) Write a relational algebra expression that satisfies this query? Find the distinct names of all students that take more than three courses and do not major in "Philosophy". Submit your answer as one or more LaTeX expression in the answer field below.
Consider the following relational schema and answer the following questions. Employee (Employee_Id, First_Name, Last_Name, Email, Phone_Number, Hire_Date, Job_Id, Salary, Commission_Pct, Manager_Id, Department_Id) a. Write a query to get the average salary and number of employees working the department 90. b. Write a query to get the highest, lowest, sum, and average salary of all employees. c. Write a query to get the number of employees with the same job. d. Write a query to get the difference between the highest and lowest salaries.
Consider the following relational schema:Student (sid, sname, dept)Enroll (cid, sid, grade, semester)Course (cid, cname, dept, credit)Prereq (cid, pid) Write the following queries in Relational Algebra expression: a) For students who have received an A in a course, return name of students and titleof the course. b) Find name and id of students taken at least one of the prerequisite of CS595course and got an A grade in this prerequisite course.
(d) Write an SQL statement, using the inner join construct, that will, for the lecturer John Smith, list in alphabetical order the students taking any module which he teaches. (e) What information does the output from the following SQL query provide? SELECT Lecturer, COUNT(DISTINCT Student) FROM class INNER JOIN staff ON class.Module = staff.Module WHERE Grade < 40 GROUP BY Lecturer; (f) Write an SQL query which would obtain the following information: for each lecturer, what is the average grade obtained by students across all of the modules which they have taught?
Consider the following sales relational database schema for sales. Item (ItemNo: integer, ItemName:string, type:string) Customer (CID:integer, Cname:string, gender: character{ ’F’-Female, ‘M’-Male}) Sales (SalesID:integer, ItemNo:ineteger, CID:intger, price:double) Write the following queries in SQL. Display ItemName and type for all items bought by female customers. Display SalesID and ItemNo of the item with the lowest price.
B2. Consider the following SQL query in the STUDENT relation.SELECT SNO FROM STUDENTWHERE (CR_HOURS > 12 OR MAJOR != “DATABASE”)AND DNAME = “IT”AND (MAJOR = “DATABASE” OR CR_HOURS > 12); a. Simplify the query using idempotency rules b. Draw the relational algebra tree for the above-simplified query.
Let's wa(k through a review of basic SQL syntax, using as an example the database that was mentionedearlier. This database has the following simple structure(* indicates a primary key):Courses: CourseID*, CourseName, TeacherIDTeachers: TeacherID*, TeacherNameStudents; StudentID*, StudentNameStudentCourses: CourseID*, StudentID*Using the above table, implement the following queries.Query 1: Student Enrollment Query 2: Teacher Class Size