SQL Online Quiz

Q 1 - 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 would display names of all the students whose email ids are not provided?

A - select first_name, last name from students where email = 0;

B - select first_name, last name from students where email = ‘ ‘;

C - select first_name, last name from students where email is null;

D - select first_name, last name from students where email = ‘null’;

Q 2 - What is returned by TRUNC(789.8389, 2)?

A - 789.84

B - 789.83

C - 78

D - 789.00

Q 3 - Which of the following is true about Cartesian Products?

A - A Cartesian product is formed when a join condition is omitted.

B - A Cartesian product is formed when a join condition is valid.

C - Some rows in the first table are joined to all rows in the second table.

D - All rows in the first table are joined to some rows in the second table.

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 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 5 - 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 6 - Which of the following is true about inserting news rows to a table?

A - You must list values in the default order of the columns in the table.

B - You can also list the columns in the INSERT clause.

C - You can use the INSERT statement to add rows from one table to another.

D - All of the above.

Q 7 - Which statement allows conditional update, or insertion of data into a table simultaneously?

A - INSERT statement

B - MERGE statement

C - UPDATE statement

D - None of the above

Q 8 - Which of the following is not true about a FOREIGN KEY constraint?

A - It is a referential integrity constraint.

B - It establishes a relationship between a primary key or a unique key in the same table or a different table.

C - A foreign key value cannot be null.

D - A foreign key value must match an existing value in the parent table.

Q 9 - Which of the following code will delete a sequence named loc_seq?

A - delete sequence loc-seq;

B - drop sequence loc_seq;

C - delete primary key loc_sec;

D - drop primary key loc_sec;

Q 10 - Which of the following statements allows William to change his database user account password to bill?

A - create user william identified by bill;

B - alter user william identified by bill

C - create user william password bill;

D - alter user william password bill;