What is the correct statement for describing the UNION operation ?

1. It combines the rows of any two different queries
2. It combines the unique rows of two different queries which have the same set of attributes in the select clause
3. It combines the rows of two different queries which have the same condition in the where clause
4. It gives the Cartesian product of the results of any two queries

What is the correct statement for describing the INTERSECT operation?

1. It returns the common values from the results of any two different queries
2. It returns the common rows of two different queries which have the same set of attributes in the select clause
3. It returns the common rows of two different queries which have the same condition in the where clause
4. None of these

What is the other name of MINUS operator?

1. UNION
2. UNION ALL
3. EXCEPT
4. INTERSECT

Examine the structure of the EMPL and DEPT tables:

Table : EMPL

Table : DEPT

Evaluate this SQL statement :

SELECT employee_id, e.department_id, department_ name, salary 
FROM EMPL e, DEPT d
WHERE e.department_id = d.department_id;

Which SQL statement is equivalent to the above SQL statement ?

(a)

SELECT employee_id, department_id, department_name, salary 
FROM EMPL
WHERE department_id MATCHES department_id of DEPT;

(b)

SELECT employee_id, department_id, department_name,salary 
FROM EMPL
NATURAL JOIN DEPT;

(c)

SELECT employee_id, d.department_id, department_name,salary
FROM EMPL e 
JOIN DEPT d 
ON e.department_id = d.department_id;

(d)

SELECT employee_id, department_id, department_name,salary
FROM EMPL 
JOIN DEPT 
USING (e. department _id, d.department_id);