Question 2: Relational Model / Relational Algebra Consider the following schema, Sailors(sid: integer, sname: string, rating: integer, age: real); Boats(bid: integer, bname: string, color: string); Reserves(sid: integer, bid: integer, day: date). Symbols you may need: n --U -- ở -- TI -- A -P You use anything that we covered in the slides. 1. Find the names of sailors who reserved a blue boat, have rating at least 8 and older than 40. 2. Find the names of sailors who reserved only blue boats. 3. Find the names of sailors who reserved at least two boats. (Similar to our example of "Find the students who earned at least two As")

Question 2: Relational Model / Relational Algebra Consider the following schema, Sailors(sid: integer, sname: string, rating: integer, age: real); Boats(bid: integer, bname: string, color: string); Reserves(sid: integer, bid: integer, day: date). Symbols you may need: n --U -- ở -- TI -- A -P You use anything that we covered in the slides. 1. Find the names of sailors who reserved a blue boat, have rating at least 8 and older than 40. 2. Find the names of sailors who reserved only blue boats. 3. Find the names of sailors who reserved at least two boats. (Similar to our example of "Find the students who earned at least two As")

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Consider the following relational database schema that contains information about employees and projects to which they are assigned. Emp (eid, lastname, gender, DOB) Assign (eid, pid, hours) Proj (pid, pname, budget, manager_eid) Answer the following questions. (a) Find two superkeys in the Proj table — both of these two superkeys should NOT be same as the primary key. You should use appropriate set notation if the superkey contains multiple attributes. (b) Suppose the Emp and Proj tables have been created appropriately. Define (i.e., create) the Assign table in SQL (Just create only one table.) You should follow all the requirements discussed in the class. (c) Suppose in the Proj table a project has changed pid from P06 to P07. From the perspective of integrity constraints, how should this modification be handled?
Consider a “Digital Games” database with the following relations and attributes: Gamer: (UserID, Name, Age, Address, City, Favorite-Game, Rank) Game: (GameID, Name, Company, Release-Year, Version) Store: (StoreID, Name, Address, City) WhereToFind: (GameID, StoreID, Price) Category: (GameID, Category-Name) From the relational schemas illustrated above, use the different relational algebra operators and operations (ρ, σ, π, ⋂, ⋃, -, ⨝) discussed in class to build the following queries:1. List -by name and ID- each gamer who lives in the city of Chicago, with a rank of 5, and is aged between 15 (included) and 30 (included).2. List games -by name and release year- that are not in the “Action” category3. Since each game can fall within several categories, list games -by name and release year- that are in the “Action” category and also in the “Role-Playing” category4.…
You are given the following schema of a University, where primary keys of each table areunderlined and symbol (#) symbolises foreign keys:Student (student_id, first_name, last_name, date_of_birth)Course (course_id, #professor_id, course_name, credits, programme)Exam (#student_id, #course_id, exam_date, grade)Professor (professor_id, first_name, last_name, research_field) -Use RELATIONAL ALGEBRA to write the following queries:a) Find names and surnames of professors, who teach a course in "Biology" programmeb) Find the student IDs and names of students who have not taken any exam (from any course)c) Find student IDs of students who have passed every exam from "Data Science" programmed) Find the course IDs and names of courses that have been passed by at least two differentstudents (If a course was taken, it means that a student wrote an exam on that course)
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 Voter (Voter_id, Voter_name, Age,Gender, constituency, Image, status) Candidate (Candidate_id, Candidate_name, Age, Sex, constituency, Party_id) Party (Party_id, Party_name, President_name) Vote(Voter_id, Candidate_id) Write the Following query into relational algebra. The key attribute is underlined. (i) Retrieve all-female candidate details. (ii) Retrieve all-female senior citizen voter details. (iii) Retrieve the candidate's name and their party president's name. (iv) Retrieve the total number of male candidates.
Database Systems Question 6. Consider the following relation: Invoice(Order_ID, Order_Date, Customer_ID, Customer_Name,Customer_Address,Product_ID, Product_Desc, Price, Order_Quantity) FD1 - Order_ID -> Order_Date, Customer_ID, Customer_Name, Customer_Address FD2 - Customer_ID -> Customer_Name, Customer_Address FD3 - Product_ID -> Product_Description, Price FD4 - Order_ID, Product_ID -> Order_Quantity What are the candidate keys of this relation? Give reasons to explain if this is in 1NF or not. If not, decompose it to 1NF. Give reasons to explain if this is in 2NF or not. If not, decompose it to 2NF. Give reasons to explain if this is in 3NF or not. If not, decompose it to 3NF.
Q3: Emp (Eno, Ename, Title, City) Project(Pno, Pname, Budget, City) Works(Eno, Pno, Resp, Dur) SELECT Ename, Pname FROM Emp e, Works w, Project p WHERE e.Eno = w.Eno AND e.city = p.Eno AND p.city = Newark AND w.Dur > 40 Given the database schema and the query above and knowing that only 1% of the employees work on a project for 40 months or more, propose an optimized query plan and discuss the indexes needed
You are given the following schema of a University, where primary keys of each table areunderlined and symbol (#) symbolises foreign keys:Student (student_id, first_name, last_name, date_of_birth)Course (course_id, #professor_id, course_name, credits, programme)Exam (#student_id, #course_id, exam_date, grade)Professor (professor_id, first_name, last_name, research_field) -Use DOMAIN or TUPLE RELATIONAL CALCULUS to write thefollowing queries:a) Find the last names of professors who have taught a course with 6 creditsb) Find all student IDs of students who are born before January 1, 1999 or have passed at leastone exam with a 10c) Find the last names of professors who have never taught a coursed) Find the last name(s) of the professor(s) who teach the most courses
Subject: Database Management System Consider the following relations: PERSON(P_id,_F_name, L_name,Occupation, Salary, City) ORDER(O_id, P_id, Item, Quantity, Price, Order_date) The Primary Keys are P_id and O_id respectively. Express the following queries in SQL and Relational Algebra. a) Find the person's name and city whose name starts with S. b) Find the person with the highest salary. c) Find the average salary for each Occupation. d) Find the detail of the person who has ordered any item. e) Find the name of the person who has ordered in the same date. f) Find the game of the person who hasn't ordered any item. g) Find the highest ordered item. h) Find the detail of Item with lowest Price.
Mapping er dig to Relational Model @* Give correct a correct Answer and get up vote else I will give downvoted...
Answer the following questions : In real-world data, tuples with missing values for some attributes are a common occurrence. Describe various methods for handling this problem. The following data (in increasing order) represent the attribute age: 13, 15, 16, 16, 19, 20, 20, 21, 22, 22, 25, 25, 25, 25, 30, 33, 33, 35, 35, 35, 35, 36, 40, 45, 46, 52, 70 Use smoothing by bin means to smooth these data, using a bin depth of 3. Illustrate your steps. Comment on the effect of this technique for the given data. How might you determine outliers in the data? What other methods are there for data smoothing?
Q3: From the mentioned below discuss which model is more suitable for storing data. And what are the draw backs of other model which are not selected by you for storing data?i. Hierarchal modelii. Network modelii. Relational model