SELECT T1.stu_fname FROM student AS T1 JOIN enroll AS T2 ON T1.stu_num  =  T2.stu_num GROUP BY T2.stu_num HAVING count(*)  =  1
Find the first names of students who took exactly one class.
SELECT T1.stu_fname FROM student AS T1 JOIN enroll AS T2 ON T1.stu_num = T2.stu_num GROUP BY T2.stu_num HAVING count ( * ) = 1
select t1 . stu_fname from student as t1 join enroll as t2 on t1 . stu_num = t2 . stu_num group by t2 . stu_num having count ( * ) = value
Find the first names of students who took exactly one class .