Tell me Krystel's date of registration.
select date_of_registration from students where personal_name = "Krystel"
How about her dates of enrollment and completion?
select t1.date_of_enrolment, 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 = "Krystel"
How about the dates of enrollment and completion of the student with family name "Zieme" and personal name "Bernie"?
select t1.date_of_enrolment, t1.date_of_completion from student_course_enrolment as t1 join students as t2 on t1.student_id = t2.student_id where t2.family_name = "Zieme" and t2.personal_name = "Bernie"