Question: What are the completion dates of all the tests that have result "Fail"?
Schema: create table student_tests_taken (registration_id varchar, test_result varchar, PRIMARY KEY (registration_id)); create table student_course_enrolment (date_of_completion varchar, registration_id varchar, PRIMARY KEY (date_of_completion))
SQL: select t1.date_of_completion from student_course_enrolment as t1 join student_tests_taken as t2 on t1.registration_id = t2.registration_id where t2.test_result = "fail"