DTBase

A UNION query is which of the following?

• Combines the output from two queries and must include the same number of columns

• Combines the output from multiple queries and must include the same number of columns

• Combines the output from multiple queries and does not have to include the same number of columns

• Combines the output from two queries and does not have to include the same number of columns

In the given query which of the keywords has to be inserted? INSERT INTO employee ___ (1002, Joey, 2000);

• Value

• Field

• Relation

• Table

Which of the following relations is in Third normal form (3NF)?

• R(ABCD) FD’s: AB -> C; BCD -> A; D -> A; B -> C

• R(ABCD) FD’s: C -> B; B -> A; AC -> D; AC -> B

• R(ABCD) FD’s: ACD -> B; AC -> D; D -> C; AC -> B

• R(ABCD) FD’s: AB -> C; ABD -> C; ABC -> D; AC -> D

Which of the following is NOT true about SQL Subqueries?

• Subqueries are executed first.

• None of these.

• They are nested queries.

• Only one subquery can be nested.

This graphic indicates:

• a student cannot own a car.

• That a student can own 0, 1 or many cars.

• A car can be owned by many students

• A student can own many cars and a car can be owned by many students.

Which of the following statements is NOT true about subqueries?

• Subqueries may occur in other places than the WHERE clause.

• Subqueries can be added with an ORDER BY clause.

• Subqueries cannot be nested multiple times

• Subqueries can be used to compare an expression to the result of the query.

Suppose relations R(A, B) and S(B, C, D) are as follows: Compute the full outer join on B, the left outer join on B, and the right outer join on B. In each case, R is the left operand and S is the right operand. Find the correct statement in the list below.

• The full outer join has 3 NULL’s

• The full outer join has 6 tuples

• The full outer join has 3 tuples

• The full outer join has 2 NULL’s

In ERD, what is the meaning of the rounded arrow?

• One or many

• Many

• One and only one

• One or Zero

Supposed we have a table staffs containing the first and last name of all staffs in USTH. Write a query to return find the official email of each person, given that the domain is @usth.edu.vn and the mail is of the following format: [e-mail]

• SELECT first_name, last_name, concat(last_name, ‘.’, first_name, ‘@usth.edu.vn’) AS Official_mail FROM Staffs

• SELECT first_name, last_name, concat(last_name, ‘.’, first_name) AS Official_mail FROM Staffs;

• All of these are correct

• SELECT first_name, last_name, distinct(first_name) AS Official_mail FROM Staffs;

Supposed we have a table Employee that contains the id (emp_id), name(emp_name) and working experience (experience) of each employee in a company. Write a query to find the second employee in terms of experience in increasing order? (first being the one with max experience).

• SELECT emp_id, MAX(experience) AS second_max_exp FROM Employee WHERE experience < (SELECT MAX(experience) FROM Employee);

• All are correct

• SELECT emp_id, experience AS second_max_exp FROM Employee WHERE experience < (SELECT MAX(experience) FROM Employee);

• SELECT emp_id, experience AS second_max_exp FROM Employee WHERE experience > (SELECT MAX(experience) FROM Employee);