Q 1 - Which of the following is not true about Natural Joins?

A - Natural join is based on all columns in two tables having same name

B - It selects rows from the two tables having different values in the matched columns.

C - If columns having same names have different data types, it returns error.

D - None of the above.

Q 2 - Consider the following schema −

HONOURS_SUBJECT(subject_code, subject_name, department_head);

LOCATIONS(subject_code, department_name, location_id, city);

Which query will perform a natural join between the HONOURS_SUBJECT table and the LOCATIONS table?

A - select subject_code, subject_name, location_id, city from honours_subject cross join locations;

B - select subject_code, subject_name, location_id, city from honours_subject join locations;

C - select subject_code, subject_name, location_id, city from honours_subject outer join locations;

D - select subject_code, subject_name, location_id, city from honours_subject natural join locations;

Q 3 - Which of the following is not true about USING clause?

A - When more than one column has the same name, USING clause is used for specifying the column to be joined by equijoin.

B - It is used for matching one column only.

C - You can use a table name or alias in the referenced columns.

D - The NATURAL JOIN and the USING clauses are mutually exclusive.

Q 4 - Consider the following schema −

HONOURS_SUBJECT(subject_code, subject_name, department_head);

LOCATIONS(subject_code, department_name, location_id, city);

Select the right query for retrieving records from the tables HONOURS_SUBJECT and LOCATIONS with the USING clause

A - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h join location l using(subject_code);

B - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h natural join location l using(subject_code);

C - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h, location l using(subject_code);

D - None of the above.

Q 5 - Which of the following is true about SQL joins?

A - The join condition is not separated from other search conditions in a query.

B - The ON clause makes code difficult to understand.

C - The join condition for natural join is basically an equijoin of all columns with same name.

D - None of the above.

Q 6 - Consider the following schema −

HONOURS_SUBJECT(subject_code, subject_name, department_head);

LOCATIONS(subject_code, department_name, location_id, city);

Select the right query for retrieving records from the tables HONOURS_SUBJECT and LOCATIONS with the ON clause

A - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h join location l on(h.subject_code = l.subject_code);

B - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h join location l on(subject_code);

C - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h, location l on(subject_code);

D - None of the above.

Q 7 - Which of the following is not true about the ON clause?

A - ON clause is used to specify conditions or specify columns to join.

B - ON clause makes the query easy to understand.

C - ON clause does not allow three way joins.

D - None of the above.

Q 8 - Which of the following is not true about SQL joins?

A - An inner join is a join of two tables returning only matching rows.

B - A left or right outer join returns the results of the inner join as well as the unmatched rows in the left or right table respectively.

C - A full outer join returns results of an inner join as well as the results of a left and right join.

D - None of the above.

Q 9 - Consider the following schema −

HONOURS_SUBJECT(subject_code, subject_name, department_head);

LOCATIONS(subject_code, department_name, location_id, city);

Select the right query for retrieving records from the tables HONOURS_SUBJECT and LOCATIONS with a left outer join

A - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h left outer join location l on(h.subject_code = l.subject_code);

B - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h left outer join location l on(subject_code);

C - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h left join location l on(h.subject_code = l.subject_code);

D - None of the above.

Q 10 - Consider the following schema −

HONOURS_SUBJECT(subject_code, subject_name, department_head);

LOCATIONS(subject_code, department_name, location_id, city);

Select the right query for retrieving records from the tables HONOURS_SUBJECT and LOCATIONS with a right outer join

A - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h on right outer join location l where(h.subject_code = l.subject_code);

B - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h outer join location l on(subject_code);

C - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h right outer join location l on(h.subject_code = l.subject_code);

D - None of the above.

Q 11 - Consider the following schema −

HONOURS_SUBJECT(subject_code, subject_name, department_head);

LOCATIONS(subject_code, department_name, location_id, city);

Select the right query for retrieving records from the tables HONOURS_SUBJECT and LOCATIONS with a full outer join

A - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h full outer join location l on(h.subject_code = l.subject_code);

B - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h full outer join location l on(subject_code);

C - select h.subject_name, l.department_name, h.department_head, l.city from honours_subject h full outer join location l where (h.subject_code = l.subject_code);

D - None of the above.

Q 12 - Which of the following is true about a group function?

A - Group functions operate on sets of rows to produce multiple results per group.

B - DISTINCT keyword makes a group function consider duplicate values.

C - Group functions ignore null values.

D - None of the above.

Q 13 - Which of the following is not a group function?

A - SUM

B - NVL

C - COUNT

D - MIN

Q 14 - Which of the following functions can be used on both numeric as well as non-numeric data?

A - COUNT

B - AVG

C - STDDEV

D - VARIANCE

Q 15 - Which of the following is not true about the MAX and MIN functions?

A - Both can be used for any data type.

B - MAX returns the maximum value.

C - MIN returns the minimum value.

D - All are true.

Q 16 - Which of the following is not true about the COUNT function?

A - COUNT(*) returns the number of rows in the table.

B - COUNT(exp) returns the number of rows with non-null values for the exp.

C - COUNT(DISTINCT exp) returns the number of unique, non-null values in the column.

D - All are true.

Q 17 - You want to calculate the sum of commissions earned by the employees of an organisation. If an employee doesn’t receive any commission, it should be calculated as zero. Which will be the right query to achieve this?

A - select sum(nvl(commission, 0)) from employees;

B - select sum(commission, 0) from employees;

C - select nvl(sum(commission), 0) from employees;

D - None of the above.

Q 18 - Which of the following query will result in an error?

A - select dept_id, avg(salary) from employees group by dept_id;

B - select avg(salary) from employees group by dept_id;

C - select dept_id, job_id, avg(salary) from employees group by dept_id, job_id;

D - select dept_id, count(name) from employees;

Q 19 - Consider the following schema −

STUDENTS(student_code, first_name, last_name, email, 
         phone_no, date_of_birth, honours_subject, percentage_of_marks);

Which of the following query will correctly list the average percentage of marks in each honours subject, when the average is more than 50 percent?

A - select honours_subject, avg(percentage_of_marks) from students where avg(percentage_of_marks) > 50.0 group by honours_subject;

B - select honours_subject, avg(percentage_of_marks) from students having avg(percentage_of_marks) > 50.0 group by honours_subject;

C - select honours_subject, avg(percentage_of_marks) from students group by honours_subject having avg(percentage_of_marks) > 50.0;

D - None of the above.

Q 20 - Which of the following is not true about a subquery?

A - A subquery is a SELECT statement embedded in a clause of another SELECT statement.

B - The subquery executes before the main query.

C - The result of the main query is returned to the subquery.

D - All of the above.

Q 21 - A subquery can be placed in which of the SQL clauses?

A - The WHERE clause

B - The HAVING clause

C - The FROM clause

D - All of the above.

Q 22 - Consider the following schema −

STUDENTS(student_code, first_name, last_name, email, 
         phone_no, date_of_birth, honours_subject, percentage_of_marks);

Which of the following query will correctly display name of all the students who got more marks than the student ‘0215/15’?

A -

select first_name, last_name from students 

where percent_of_marks > 
	(select percentage_of_marks from students
		where student_code = ‘0215/15’);

B -

select first_name, last_name from students 
having percent_of_marks > 
	(select percentage_of_marks from students
		where student_code = ‘0215/15’);

C -

select first_name, last_name from students 
using percent_of_marks > 
	(select select percentage_of_marks from students
		where student_code = ‘0215/15’);

D - None of the above.

Q 23 - Which of the following is true about subqueries?

A - Subqueries could be used for Top-N analysis.

B - Subqueries can be of two types – single-row subquery and multiple-row subquery.

C - The outer and inner queries can get data from different tables.

D - All of the above.

Q 24 - Which of the following is not true about single-row subqueries?

A - Single row subqueries return one row from the inner SELECT statement.

B - Single row subqueries return one row from the outer SELECT statement.

C - Single row subqueries use single-row comparison operators.

D - All of the above.

Q 25 - You want to calculate the minimum percentage of marks obtained under each honours group students, where the minimum marks is more than the minimum marks in economics department. Under which clause should the subquery be?

A - WHERE clause

B - FROM clause

C - HAVING clause

D - None of the above.