CREATE TABLE Courses (course_id NUMBER, author_id NUMBER, subject_id NUMBER, course_name VARCHAR2, course_description VARCHAR2)
CREATE TABLE Students (student_id NUMBER, date_of_registration DATETIME, date_of_latest_logon DATETIME, login_name VARCHAR2, password VARCHAR2, personal_name VARCHAR2, middle_name VARCHAR2, family_name VARCHAR2)
CREATE TABLE Student_Course_Enrolment (registration_id NUMBER, student_id NUMBER, course_id NUMBER, date_of_enrolment DATETIME, date_of_completion DATETIME)
CREATE TABLE Student_Tests_Taken (registration_id NUMBER, date_test_taken DATETIME, test_result VARCHAR2)
CREATE TABLE Course_Authors_and_Tutors (author_id NUMBER, author_tutor_ATB VARCHAR2, login_name VARCHAR2, password VARCHAR2, personal_name VARCHAR2, middle_name VARCHAR2, family_name VARCHAR2, gender_mf VARCHAR2, address_line_1 VARCHAR2)
CREATE TABLE Subjects (subject_id NUMBER, subject_name VARCHAR2)

A bar chart for finding the number of the latest logon date of the students whose family name is 'Jaskolski' or 'Langosh', and I want to show y axis in descending order.
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