CREATE TABLE Subjects (subject_id INT, subject_name VARCHAR)
CREATE TABLE Courses (course_id INT, author_id INT, subject_id INT, course_name VARCHAR, course_description 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 Student_Tests_Taken (registration_id INT, date_test_taken DATETIME, test_result 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)

A bar chart for what are the number of the dates of the latest logon of the students with family name 'Jaskolski' or 'Langosh'?, and sort in descending by the y-axis.
SELECT date_of_latest_logon, COUNT(date_of_latest_logon) FROM Students WHERE family_name = "Jaskolski" OR family_name = "Langosh" ORDER BY COUNT(date_of_latest_logon) DESC
SELECT "date_of_latest_logon", COUNT("date_of_latest_logon") FROM "Students" WHERE "Jaskolski" = "family_name" OR "Langosh" = "family_name" ORDER BY COUNT("date_of_latest_logon") DESC NULLS LAST