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 students in descending order of percentage of marks?

A - select first_name, last name, percentage_of_marks from students order by percentage_of_marks;

B - select first_name, last name, percentage_of_marks order by percentage_of_marks desc from students;

C - select first_name, last name, percentage_of_marks from students order by percentage_of_marks desc;

D - select first_name, last name, percentage_of_marks from students order by percentage_of_marks descending;

Q 2 - Which of the following is not true about single row functions?

A - They operate on single rows only and return one result per row.

B - They accept arguments that could be a column or any expression.

C - They cannot be nested.

D - They may modify the data type.

Q 3 - 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 4 - 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 5 - 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 6 - Which of the following is true about removing rows from a table?

A - You remove existing rows from a table using the DELETE statement

B - No rows are deleted if you omit the WHERE clause.

C - You cannot delete rows based on values from another table.

D - All of the above.

Q 7 - Consider the following schema −

LOCATIONS(subject_code, department_name, location_id, city);

Which code snippet will alter the table LOCATIONS and add a column named Address, with datatype VARCHAR2(100)?

A - ALTER TABLE locations ADD (address varchar2(100));

B - ALTER TABLE locations ADD COLUMN(address varchar2(100));

C - MODIFY TABLE locations ADD COLUMN (address varchar2(100));

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 retrieve data from the view all_marks_english, created in the previous question?

A - select view all_marks_english;

B - select from all_marks_english;

C - retrieve from all_marks_english;

D - select * from all_marks_english;

Q 10 - Which of the following code would grant the role student_admin to a user named william?

A - grant student_admin to william;

B - grant to william student_admin;

C - grant william student_admin;

D - None of the above.