CREATE TABLE Courses (course_id INT, author_id INT, subject_id INT, course_name VARCHAR, course_description VARCHAR)
CREATE TABLE Student_Tests_Taken (registration_id INT, date_test_taken DATETIME, test_result VARCHAR)
CREATE TABLE Students (student_id INT, date_of_registration DATETIME, date_of_latest_logon DATETIME, login_name VARCHAR, password VARCHAR, personal_name VARCHAR, middle_name VARCHAR, family_name VARCHAR)
CREATE TABLE Subjects (subject_id INT, subject_name VARCHAR)
CREATE TABLE Student_Course_Enrolment (registration_id INT, student_id INT, course_id INT, date_of_enrolment DATETIME, date_of_completion DATETIME)
CREATE TABLE Course_Authors_and_Tutors (author_id INT, author_tutor_ATB VARCHAR, login_name VARCHAR, password VARCHAR, personal_name VARCHAR, middle_name VARCHAR, family_name VARCHAR, gender_mf VARCHAR, address_line_1 VARCHAR)

List the number of completion students in each day and group by date of completion in a line chart, and show from high to low by the X-axis please.
SELECT date_of_completion, COUNT(date_of_completion) FROM Student_Course_Enrolment GROUP BY date_of_completion ORDER BY date_of_completion DESC
SELECT "date_of_completion", COUNT("date_of_completion") FROM "Student_Course_Enrolment" GROUP BY "date_of_completion" ORDER BY "date_of_completion" DESC NULLS LAST