PQ Quiz 2

A.... is a property of the entire relation, rather than
of the individual tuples in which each tuple is unique.

• Rows

• Key

• Attribute

• Fields

What is the result of the following query?
SELECT studentdatabasename
FROM RDBMS
WHERE marks > SOME (SELECT marks
FROM student
WHERE SECTION = 'c');

• The query gives all the studentdatabasename for
  which marks are greater than all the students in
  section c

• The query gives all the studentdatabasename for
  which the marks are greater than at least on
  student in section c

• The query gives all the studentdatabasename for
  which the marks are less than all the students in
  section c

• The query is syntactically incorrect

What is the correct answer to describe the following
query.
SELECT name
FROM instructor
WHERE salary IS NOT NULL;

• Tuples with null value

• Tuples with no null values

• Tuples with any salary

• All of the mentioned

Which of the following MySQL aggregate functions is used to calculate the average?

• COUNT()

• EVERAGE()

• AVERAGE()

• AVG()

From the query below, how many rows are selected?
SELECT Name
FROM instructor
WHERE salary > SOME (SELECT salary FROM
instructor WHERE dept_name = 'Comp.Sci.');

• The number of rows selected depends on the data
  in the 'instructor' table and the comparison of
  salaries.

• The number of rows selected is O

• The number of rows selected is always 10

• The number of rows selected is 100

The query given below will not give an error. Which one of the following has to be replaced to get the desired output?
SELECT ID, name, dept name, salary * 1.1
WHERE instructor;

• Salary*1.1

• ID

• Where

• Instructor

What is the purpose of the MySQL AUTO_INCREMENT attribute?

• The purpose of the MySQL AUTO_INCREMENT
  attribute is to delete existing rows in a table.

• The purpose of the MySQL AUTO_INCREMENT
  attribute is to update the values in a column.

• The purpose of the MySQL AUTO_INCREMENT
  attribute is to sort the rows in a table.

• The purpose of the MySQL AUTO_INCREMENT
  attribute is to automatically generate a unique
  value for a column whenever a new row is inserted
  into the table.

From the script,
CREATE TABLE department
(dept_name VARCHAR (20),
building VARCHAR (15),
budget NUMBER,
PRIMARY KEY (dept_name));
CREATE TABLE course
(course_id VARCHAR (7),
title VARCHAR (50),
dept_name VARCHAR (20),
credits NUMERIC (2,0),
PRIMARY KEY (course_id),
FOREIGN KEY (dept_name)
department);
CREATE TABLE instructor
(ID VARCHAR (5),
name VARCHAR (20) NOT NULL,
dept_name VARCHAR (20),
salary NUMERIC (8,2),
FOREIGN KEY (dept_name)
CREATE TABLE SECTION
(course_id VARCHAR (8),
sec_id VARCHAR (8),
semester VARCHAR (6),
YEAR NUMERIC (4,0),
building VARCHAR (15),
department);
room_number VARCHAR (7),
time_slot id VARCHAR (4),

PRIMARY KEY (ID, course_id, sec_id, semester, YEAR),
FOREIGN KEY (course_id, sec_id, semester, YEAR)
REFERENCES SECTION,
FOREIGN KEY (ID) _____instructor);
In order to include an attribute Name to the teaches
relation which of the following command is used?

• Alter table teaches include Name;

• Alter table teaches add Name;

• Alter table teaches add Name varchar;

• Alter table teaches add Name varchar(20);

Which of the following operations are associative

• Natural joins

• Theta joins

• Both the mentioned

• None of the mentioned

Choose the correct option regarding the query
SELECT branch_name, COUNT (DISTINCT
customer_name)
FROM depositor, account
WHERE depositor.account_number =
account.account_number
GROUP BY branch_id
HAVING avg(balance) = 10000;

• The having clause allows only those tuples that
  have an average balance of 10000

• The having clause checks whether the query result
  is true or not

• The having clause does not check for any condition

• None of the mentioned