CREATE TABLE student_course_registrations (student_id VARCHAR(255), course_id VARCHAR(255), registration_date VARCHAR(255)); CREATE TABLE courses (course_id VARCHAR(255), course_name VARCHAR(255))
List the id of students who registered course statistics in the order of registration date.
    
SQL: SELECT T2.student_id FROM courses AS T1 JOIN student_course_registrations AS T2 ON T1.course_id = T2.course_id WHERE T1.course_name = "statistics" ORDER BY T2.registration_date