Recent questions tagged korth-edition6 / GATE Overflow for GATE CSE

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31

DBMS Korth Edition 6 Exercise 6 Question 19 (Page No. 254)
Give a tuple-relational-calculus expression to find the maximum value in relation r (A).

Give a tuple-relational-calculus expression to find the maximum value inrelation r (A).

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32

DBMS Korth Edition 6 Exercise 6 Question 15 (Page No. 253-254)
Consider the employee database shown here. Give expressions in tuple relational calculus and domain relational calculus for each of the following queries: a. Find the names of all employees who work for First Bank Corporation . b ... (person name, company name, salary) company (company name, city) manages (person name, manager name)

Consider the employee database shown here. Give expressions in tuplerelational calculus and domain relational calculus for each of the followingqueries:a. Find the names ...

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33

DBMS Korth Edition 6 Exercise 6 Question 14 (Page No. 253)
Consider the following relational schema for a library: member(memb_no, name, dob) books(isbn, title, authors, publisher) borrowed(memb_no, isbn, date) Write the following queries in relational algebra. a. Find the names of members ... if a member does not borrow any books, then that member does not appear in the borrowed relation at all.

Consider the following relational schema for a library:member(memb_no, name, dob) books(isbn, title, authors, publisher) borrowed(memb_no, isbn, date)Write the following ...

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34

DBMS Korth Edition 6 Exercise 6 Question 13 (Page No. 253)
Consider the relational database shown here. Give a relational-algebra expression for each of the following queries: a. Find the company with the most employees. b. Find the company with the smallest payroll. c. Find those ... works (person name, company name, salary) company (company name, city) manages (person name, manager name)

Consider the relational database shown here. Give a relational-algebraexpression for each of the following queries:a. Find the company with the most employees.b. Find the...

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35

DBMS Korth Edition 6 Exercise 6 Question 12 (Page No. 253)
Using the university example, write relational-algebra queries to find the course sections taught by more than one instructor in the following ways: a. Using an aggregate function. b. Without using any aggregate functions.

Using the university example, write relational-algebra queries to find thecourse sections taught by more than one instructor in the following ways:a. Using an aggregate f...

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36

DBMS Korth Edition 6 Exercise 6 Question 11 (Page No. 252)
Consider the relational database shown here, where the primary keys are underlined. Give an expression in the relational algebra to express each of the following queries: a. Find the names of all employees who work for First Bank ... works (person name, company name, salary) company (company name, city) manages (person name, manager name)

Consider the relational database shown here, where the primary keys areunderlined. Give an expression in the relational algebra to express each ofthe following queries:a....

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37

DBMS Korth Edition 6 Exercise 6 Question 10 (Page No. 252)
Write the following queries in relational algebra, using the university schema. a. Find the names of all students who have taken at least one Comp. Sci. course. b. Find the IDs and names of all students who have ... instructor. d. Find the lowest, across all departments, of the per-department maximum salary computed by the preceding query.

Write the following queries in relational algebra, using the universityschema.a. Find the names of all students who have taken at least one Comp. Sci.course.b. Find the I...

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38

DBMS Korth Edition 6 Exercise 6 Question 9 (Page No. 252)
Describe how to translate join expressions in SQL to relational algebra.

Describe how to translate join expressions in SQL to relational algebra.

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39

DBMS Korth Edition 6 Exercise 6 Question 8 (Page No. 251)
Consider the relational database given below where the primary keys are underlined. Give an expression in tuple relational calculus for each of the following queries: a. Find all employees who work directly for Jones. b. Find all ... works (person name, company name, salary) company (company name, city) manages (person name, manager name)

Consider the relational database given below where the primary keys areunderlined. Give an expression in tuple relational calculus for each of thefollowing queries:a. Fin...

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40

DBMS Korth Edition 6 Exercise 6 Question 7 (Page No. 251)
Let R = (A, B) and S = (A,C), and let r (R) and s(S) be relations.Write expressions in relational algebra for each of the following queries: a. {< a > | ∃ b (< a, b > ∈ r ∧ b = 7)} b. {< a, b, c > | < a, b > ∈ r ∧ < ... | ∃ c (< a, c > ∈ s ∧ ∃ b1, b2 (< a, b1 > ∈ r ∧ < c, b2 > ∈ r ∧ b1 > b2))}

Let R = (A, B) and S = (A,C), and let r (R) and s(S) be relations.Writeexpressions in relational algebra for each of the following queries:a. {< a | ∃ b (< a, b ∈ r...

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41

DBMS Korth Edition 6 Exercise 6 Question 6 (Page No. 251)
Let R = (A, B, C), and let r1 and r2 both be relations on schema R. Give an expression in the domain relational calculus that is equivalent to each of the following: a. $\prod _A(r1)$ b. $\sigma _{B =17} (r1)$ c. r1 ∪ r2 d. r1 ∩ r2 e. r1 − r2 f. $\prod _{A,B}(r1) \Join \prod _{B,C}(r2)$

Let R = (A, B, C), and let r1 and r2 both be relations on schema R. Give an expression in the domain relational calculus that is equivalent to each of the following:a. $\...

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42

DBMS Korth Edition 6 Exercise 6 Question 5 (Page No. 251)
Let the following relation schemas be given: R = (A, B,C) S = (D, E, F) Let relations r(R) and s(S) be given. Give an expression in the tuple relational calculus that is equivalent to each of the following: a. $\prod _A(r)$ b. $\sigma _{B =17} (r )$ c. r × s d. $\prod _{A,F} (\sigma _{C = D}(r × s))$

Let the following relation schemas be given:R = (A, B,C)S = (D, E, F)Let relations r(R) and s(S) be given. Give an expression in the tuple relationalcalculus that is equi...

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43

DBMS Korth Edition 6 Exercise 6 Question 4 (Page No. 250)
(Division operation): The division operator of relational algebra, , is defined as follows. Let r (R) and s(S) be relations, and let S ⊆ R; that is, every attribute of schema S is also in schema R. ... using division. (By doing so, you would have shown how to define the division operation using the other relational algebra operations.)

(Division operation): The division operator of relational algebra, “÷”, isdefined as follows. Let r (R) and s(S) be relations, and let S ⊆ R; that is,every attribu...

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DBMS Korth Edition 6 Exercise 6 Question 3 (Page No. 250)
The natural outer-join operations extend the natural-join operation so that tuples from the participating relations are not lost in the result of the join. Describe how the theta-join operation can be extended so that tuples from the left, right, or both relations are not lost from the result of a theta join.

The natural outer-join operations extend the natural-join operation so thattuples from the participating relations are not lost in the result of the join.Describe how the...

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45

DBMS Korth Edition 6 Exercise 6 Question 2 (Page No. 250)
Consider the relational database given below, where the primary keys are underlined. Give an expression in the relational algebra to express each of the following queries: a. Find the names of all employees who live in the same ... works (person name, company name, salary) company (company name, city) manages (person name, manager name)

Consider the relational database given below, where the primary keys areunderlined. Give an expression in the relational algebra to express each ofthe following queries:a...

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46

DBMS Korth Edition 6 Exercise 6 Question 1 (Page No. 249)
Write the following queries in relational algebra, using the university schema. a. Find the titles of courses in the Comp. Sci. department that have 3 credits. b. Find the IDs of all students who were taught by an ... enrollment, across all sections, in Autumn 2009. g. Find the sections that had the maximum enrollment in Autumn 2009.

Write the following queries in relational algebra, using the universityschema.a. Find the titles of courses in the Comp. Sci. department that have 3 credits.b. Find the I...

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47

DBMS Korth Edition 6 Exercise 4 Question 17 (Page No. 155)
Explain why, when a manager, say Satoshi, grants an authorization, the grant should be done by the manager role, rather than by the user Satoshi.

Explain why, when a manager, say Satoshi, grants an authorization, thegrant should be done by the manager role, rather than by the user Satoshi.

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48

DBMS Korth Edition 6 Exercise 4 Question 16 (Page No. 155)
Referential-integrity constraints as defined generally involve exactly two relations. Consider a database that includes the relations shown below . Suppose that we wish to require that every name that appears in address appears in either ... (name, office, phone, salary) hourly worker (name, hourly wage) address (name, street, city)

Referential-integrity constraints as defined generally involve exactlytwo relations. Consider a database that includes the relations shown below. Suppose that we wish to ...

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49

DBMS Korth Edition 6 Exercise 4 Question 14 (Page No. 155)
Show how to define a view tot credits (year, num credits), giving the total number of credits taken by students in each year.

Show how to define a view tot credits (year, num credits), giving the totalnumber of credits taken by students in each year.

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50

DBMS Korth Edition 6 Exercise 4 Question 13 (Page No. 155)
Under what circumstances would the query select * from student natural full outer join takes natural full outer join course include tuples with null values for the title attribute?

Under what circumstances would the queryselect * from student natural full outer join takes natural full outer join courseinclude tuples with null values for the title at...

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51

DBMS Korth Edition 6 Exercise 4 Question 12 (Page No. 155)
For the database shown below, write a query to find those employees with no manager. Note that an employee may simply have no manager listed or may have a null manager. Write your query using an outer join and then write ... city) works (employee name, company name, salary) company (company name, city) manages (employee name, manager name)

For the database shown below, write a query to find those employees withno manager. Note that an employee may simply have no manager listed ormay have a null manager. Wri...

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52

DBMS Korth Edition 6 Exercise 4 Question 10 (Page No. 154)
SQL provides an n-ary operation called coalesce, which is defined as follows: coalesce(A1, A2, . . . , An) returns the first non null Ai in the list A1, A2, . . . , An, and returns null if all of A1, A2, . . ... name and address, and that the solution is correct even if some tuples in a and b have null values for attributes name or address.

SQL provides an n-ary operation called coalesce, which is defined asfollows: coalesce(A1, A2, . . . , An) returns the first non null Ai in the listA1, A2, . . . , An, and...

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53

DBMS Korth Edition 6 Exercise 4 Question 9 (Page No. 154)
SQL allows a foreign-key dependency to refer to the same relation, as in the following example: create table manager (employee name varchar(20) not null manager name varchar(20) not null, primary key employee name, foreign ... every manager also be an employee. Explain exactly what happens when a tuple in the relation manager is deleted.

SQL allows a foreign-key dependency to refer to the same relation, as in thefollowing example:create table manager(employee name varchar(20) not nullmanager name varchar(...

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DBMS Korth Edition 6 Exercise 4 Question 8 (Page No. 154)
we expect the constraint “an instructor cannot teach sections in two different classrooms in a semester in the same time slot” to hold. a. Write an SQL query that returns all (instructor, section) combinations that violate this constraint. b. Write an SQL assertion to enforce this constraint.

we expect the constraint “an instructor cannot teach sections in two different classrooms in a semester in the same timeslot” to hold.a. Write an SQL query that retur...

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55

DBMS Korth Edition 6 Exercise 4 Question 7 (Page No. 154)
Consider the relational database shown below. Give an SQL DDL definition of this database. Identify referential-integrity constraints that should hold, and include them in the DDL definition. employee (employee name, street, city) works (employee name, company name, salary) company (company name, city) manages (employee name, manager name)

Consider the relational database shown below. Give an SQL DDL definitionof this database. Identify referential-integrity constraints that should hold,and include them in ...

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56

DBMS Korth Edition 6 Exercise 4 Question 6 (Page No. 153)
Complete the SQL DDL definition of the university database shown below in figure 4.8 to include the relations student, takes, advisor, and prereq.

Complete the SQL DDL definition of the university database shown below in figure 4.8to include the relations student, takes, advisor, and prereq.

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57

DBMS Korth Edition 6 Exercise 4 Question 5 (Page No. 153)
Show how to define the view student_grades (ID, GPA) giving the gradepoint average of each student, based on the query given below 3.2; recall that we used a relation grade_points(grade, points) to get the numeric ... Make sure your view definition correctly handles the case of null values for the grade attribute of the takes relation.

Show how to define the view student_grades (ID, GPA) giving the gradepointaverage of each student, based on the query given below 3.2; recallthat we used a relation grade...

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58

DBMS Korth Edition 6 Exercise 4 Question 3 (Page No. 153)
Suppose we have three relations r (A, B), s(B, C), and t(B, D), with all attributes declared as not null. Consider the expressions r natural left outer join (s natural left outer join t), and (r natural left outer ... Is the above pattern, with C null and D not null possible in the result of the first expression? Explain why or why not.

Suppose we have three relations r (A, B), s(B, C), and t(B, D), with allattributes declared as not null. Consider the expressions• r natural left outer join (s natural ...

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59

DBMS Korth Edition 6 Exercise 4 Question 2 (Page No. 152)
Outer join expressions can be computed in SQL without using the SQL outer join operation. To illustrate this fact, show how to rewrite each of the following SQL queries without using the outer join expression. a. select* from student natural left outer join takes b. select* from student natural full outer join takes

Outer join expressions can be computed in SQL without using the SQLouter join operation. To illustrate this fact, show how to rewrite each of thefollowing SQL queries wit...

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60

DBMS Korth Edition 6 Exercise 4 Question 1 (Page No. 152)
Write the following queries in SQL: a. Display a list of all instructors, showing their ID, name, and the number of sections that they have taught. Make sure to show the number of sections as 0 for ... of instructors in each department, without using scalar sub queries. Make sure to correctly handle departments with no instructors.

Write the following queries in SQL:a. Display a list of all instructors, showing their ID, name, and the numberof sections that they have taught. Make sure to show the nu...

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author	user:martin
title	title:apple
content	content:apple
exclude	-tag:apple
force match	+apple
views	views:100
score	score:10
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is accepted	isaccepted:true
is closed	isclosed:true