Let R and S be two relations with the following schemas R (P.Q.R1,R2,R3) and S (P.Q,S1,S₂), where (P. Q) is the primary key for both schemas. Which of the following relational algebra expressions are equivalent? I 11, (RS) II. 11, (R) 11, (S) III. 1 (11, (R), (S)) IV. 11, (1, (R)-(11, (R)-11, (S))) PA I, II, and III I and III IV only I and II O I, III, and IV

Let R and S be two relations with the following schemas R (P.Q.R1,R2,R3) and S (P.Q,S1,S₂), where (P. Q) is the primary key for both schemas. Which of the following relational algebra expressions are equivalent? I 11, (RS) II. 11, (R) 11, (S) III. 1 (11, (R), (S)) IV. 11, (1, (R)-(11, (R)-11, (S))) PA I, II, and III I and III IV only I and II O I, III, and IV

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

See similar textbooks

Similar questions

Develop an Entity Relationships Diagram (ERD) based on the relational schemas in the 3NF for the starting relational schema in un-normalized form presented below. UNF:Order(OrderID, OrderDate, CustID, CustName, CustPhone, CCNum, CCExpDate, CCBank, BnkContName, BnkContPhone, CustEmail, OrderIP, SiteRefFrom, ShipStreet, ShipCity, ShipSt, ShipZip, OrderLineNum, ItemID, ItemName, ItemDesc, ItemQtyOrdered,ItemListPrice, ItemSalePrice, ItemQtyShip, ShipCharge, Tax, TotalDue)
Explain how functional dependencies may be used to indicate: • The entity sets student and teacher have a one-to-one relationship set.• Between entity setsstudent and teacher, there is a many-to-one connection set.
Consider the relation r(A, B, C), where the index is the attribute A. Give an example of a query that can only be answered by looking at the index rather than the relationship's tuples. (Index-only plans are query plans that rely just on the index rather than the actual relation.)
Consider the relations Courses1, Courses2, _Enrollment and Students. Courses cid ename Al Calculus A2 Algebra A5 English Location LI L2 L3 Student(sid, sname, age, level) Courses2 cid AS B1 B2 name English History b) Courses 1-Courses2 L3 L4 Computing L5 c) Courses Courses2 Classroom (1) Give the results of the following relational _algebra expressions: a) Teid ( name='History' OR 'Computing (Courses2)) d) Courses1 Enrollment e) Enrollment / Teid (Courses1) Enrollment sid cid 101 Al 102 A5 103 Bl 102 Al 102 A2 CARENA (2) Write the following query in Relational Algebra. a) Find the sids of students who have enrolled in course Calculus. b) Find the names of students who have enrolled in course Calculus. _c) Find the names of students who have enrolled at least one course. _d) Find the names of students who have enrolled in _Calculus or Algebra. e) Find the sids of students who have enrolled in all courses (both Courses1 and Courses2).
Transform ERD into Relation
Consider the relations Courses1, Courses2, _Enrollment and Students. Courses cid cname Al Calculus A2 Algebra A5 English Location LI L2 L3 Student(sid, sname, age, level) Courses2 cid A5 Bl B2 name English History b) Courses 1-Courses2 L3 L4 Computing L5 (1) Give the results of the following relational algebra expressions: a) Teid ( name="History' OR 'Computing (Courses2)) c) Courses Courses2 Classroom d) Courses1 Enrollment e) Enrollment / Teid (Courses1) Enrollment sid cid 101 Al 102 A5 103 B1 102 102 Al A2 (2) Write the following query in Relational Algebra. a) Find the sids of students who have enrolled in course Calculus. b) Find the names of students who have enrolled in course Calculus. c) Find the names of students who have enrolled at least one course. _d) Find the names of students who have enrolled in _Calculus or Algebra. e) Find the sids of students who have enrolled in all courses (both Courses1 and Courses2).
5
Explain how functional dependencies can be used to indicate the following: A one-to-one relationship set exists between entity sets student and Instructor. A many-to-one relationship set exists between entity sets student and instructor.
Let R be a relational schema {A, B, C, D, E, F, G} and let F be the set of functional dependencies F = {AB→C, AC→B, BC→EG, AD→E, B→DG, BE→A, AE→CG}. Find the minimal cover.
Consider the following relations for a simple airport databas Hangars (hangNo, capacity, location, status) AirplaneTypes (Model, capacity, weight) Airplanes (regNo, model, hangNO) Owners (owner, name, address, phone, ssn) Owns (regNo, ownID, startedDate) There are four foreign keys for this database: 1. The attribute hangNo of the relation Airplanes that references the relation Hangars, 2. The attribute model of the relation Airplanes that references the relation AirplaneTypes, 3. The attribute regNo of the relation Owns that references the relation Airplanes, and 4. The attribute ownID of the relation Owns that references the relation Owner. Q1: Write SQL statements to define the above relation Hangars. You should choose a suitable data type and/or daya size for each column and be sure to declare appropriate integrity constraint(s). Q2. Which of the following SQL statements is used to define the above relation Airplanes? Ensure the data type and size for each attribute are…
What is the output of an operation that begins with the execution of a Cartesian product of student and adviser and then continues with a selection operation on the result using the predicate s id = ID? Using the symbolic notation of relational algebra, this query may be expressed as s id=ID if it is given in that format (student advisor).