Examine the structure of the EMPLOYEES and DEPARTMENTS tables:
EMPLOYEES
EMPLOYEE_ID NUMBER
DEPARTMENT_ID NUMBER
MANAGER_ID NUMBER
LAST_NAME VARCHAR2(25)
DEPARTMENTS
DEPARTMENT_ID NUMBER
MANAGER_ID NUMBER
DEPARTMENT_NAME VARCHAR2(35)
LOCATION_ID NUMBER
You want to create a report displaying employee last names, department names, and locations.
Which query should you use?
A.
SELECT last_name, department_name, location_id
FROM employees , departments ;
B.
SELECT employees.last_name, departments.department_name, departments.location_id
FROM employees e, departments D
WHERE e.department_id =d.department_id;
C.
SELECT e.last_name, d.department_name, d.location_id
FROM employees e, departments D
WHERE manager_id =manager_id;
D.
SELECT e.last_name, d.department_name, d.location_id
FROM employees e, departments D
WHERE e.department_id =d.department_id;
Explanation:
:
Equijoins are also called simple joins or inner joins. Equijoin involve primary key and foreign key.
Incorrect answer :
A there is no join
B invalid syntax
C does not involve the join in the primary and foreign key
Refer : Introduction to Oracle9i : SQL, Oracle University Study Guide, 4-8
D