Databases - Upwork

Question: If E1 and E2 are relational algebra expressions, then which of the following is NOT a relational algebra expression?
A
E1 U E2

B
E1 / E2

C
E1 - E2

D
E1 x E2

Note: Not available
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Question: Which one of the following correctly selects rows from the table myTable that have null in column column1?
A
SELECT * FROM myTable WHERE column1 is null

B
SELECT * FROM myTable WHERE column1 = null

C
SELECT * FROM myTable WHERE column1 EQUALS null

D
SELECT * FROM myTable WHERE column1 NOT null

E
SELECT * FROM myTable WHERE column1 CONTAINS null

Note: Not available
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Question: A table has following values for its department field: marketing, production, production, sales, NULL, NULL, Marketing, Null What will the following query return: Select distinct(department) from employees;
A
marketing, production, sales

B
marketing, production, sales, NULL

C
marketing, production, sales, NULL, NULL

D
marketing, production, sales, NULL, Marketing

E
marketing, production, sales, NULL, NULL, Marketing

Note: Not available
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Question: Which query will display data from the Pers table relating to Analysts, Clerks and Salesmen who joined between 1/1/2005 and 1/2/2005 ?
A
select * from Pers where joining_date from '1/1/2005' to '1/2/2005', job='Analyst' or 'Clerk' or 'Salesman'

B
select * from Pers where joining_date between '1/1/2005' to '1/2/2005', job='Analyst' or job='Clerk' or job='Salesman'

C
select * from Pers where joining_date between '1/1/2005' and '1/2/2005' and (job='Analyst' or 'Clerk' or 'Salesman')

D
None of these above

Note: Not available
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Question: Consider the following tables: Books ------ BookId BookName AuthorId SubjectId PopularityRating (the popularity of the book on a scale of 1 to 10) Language (such as French, English, German etc) Subjects --------- SubjectId Subject (such as History, Geography, Mathematics etc) Authors -------- AuthorId AuthorName Country What is the query to determine which Authors have written at least 1 book with a popularity rating of less than 5?
A
select authorname from authors where authorid in (select authorid from books where popularityrating<5)

B
select authorname from authors where authorid in (select authorid from books where popularityrating<=5)

C
select authorname from authors where authorid in (select BookId from books where popularityrating<5)

D
select authorname from authors where authorid in (select authorid from books where popularityrating in (0,5))

Note: Not available
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Question: Choose the appropriate query for the Products table where data should be displayed primarily in ascending order of the ProductGroup column. Secondary sorting should be in descending order of the CurrentStock column.
A
Select * from Products order by CurrentStock,ProductGroup

B
Select * from Products order by CurrentStock DESC,ProductGroup

C
Select * from Products order by ProductGroup,CurrentStock

D
Select * from Products order by ProductGroup,CurrentStock DESC

E
None of these above

Note: Not available
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Question: Which of the following statements are incorrect regarding definition of simple and complex views?
A
A simple view is one which derives data from only one table

B
A simple view is one which contains no functions or groups of data

C
A complex view is one which derives data from many tables

D
A complex view is one which may contain functions

E
A complex view cannot contain groups of data

F
A complex view is a combination of more than one simple view

G
A table can either have a simple or complex view, not both

Note: Not available
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Question: What is a cluster?
A
Group of users

B
Group of indexes

C
Method of storing tables that are intimately related and often joined together into the same area of the disk

D
Compressed datafile

E
Segment of a partitioned table

F
Group of constraints

G
Group of databases

H
Group of roles

Note: Not available
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Question: The purpose of the domain is to constrain the set of valid values. True or false?
A
True

B
False

Note: Not available
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Question: Consider the following two tables: 1. customers( customer_id, customer_name) 2. branch ( branch_id, branch_name ) What will be the output if the following query is executed: Select *, branch_name from customers, branch
A
It will return the fields customer_id, customer_name, branch_name with a cartesian join

B
It will return the fields customer_id, customer_name, branch_id, branch_name with a cartesian join

C
It will return the fields customer_id, customer_name, branch_id, branch_name, branch_name with a cartesian join

D
It will return an empty set since the two tables do not have any common field name

E
It will return an error since * should be for queries involving one table only

Note: Not available
1. Report

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Question: If E1 and E2 are relational algebra expressions, then which of the following is NOT a relational algebra expression?

Question: Which one of the following correctly selects rows from the table myTable that have null in column column1?

Question: A table has following values for its department field: marketing, production, production, sales, NULL, NULL, Marketing, Null What will the following query return: Select distinct(department) from employees;

Question: Which query will display data from the Pers table relating to Analysts, Clerks and Salesmen who joined between 1/1/2005 and 1/2/2005 ?

Question: Choose the appropriate query for the Products table where data should be displayed primarily in ascending order of the ProductGroup column. Secondary sorting should be in descending order of the CurrentStock column.

Question: Which of the following statements are incorrect regarding definition of simple and complex views?

Question: What is a cluster?

Question: The purpose of the domain is to constrain the set of valid values. True or false?

Question: Consider the following two tables: 1. customers( customer_id, customer_name) 2. branch ( branch_id, branch_name ) What will be the output if the following query is executed: Select *, branch_name from customers, branch