Tell me Karson's registration date.
select date_of_registration from students where personal_name = "Karson"
When is his enrollment?
select t1.date_of_enrolment from student_course_enrolment as t1 join students as t2 on t1.student_id = t2.student_id where t2.personal_name = "Karson"
When is his completion?
select t1.date_of_completion from student_course_enrolment as t1 join students as t2 on t1.student_id = t2.student_id where t2.personal_name = "Karson"