In SQL, we can use the same name for multiple attributes as long as the attributes are in different relations. If two or more attributes in different relations have the same name, we need to specify them by the relation name. We can qualify the attribute name with the relation nae by prefixing the relation name to the attribute name.
SELECT EMPLOYEE.FNAME, EMPLOYEE.LNAME, EMPLOYEE.ADDRESS FROM EMPLOYEE, DEPARTMENT WHERE DEPARTMENT.DNAME='Research' AND DEPARTMENT.DNUMBER=EMPLOYEE.DNO