Challenge: Gradebook

CREATE TABLE student_grades (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT,
    number_grade INTEGER,
    fraction_completed REAL);
    
INSERT INTO student_grades (name, number_grade, fraction_completed)
    VALUES ("Winston", 90, 0.805);
INSERT INTO student_grades (name, number_grade, fraction_completed)
    VALUES ("Winnefer", 95, 0.901);
INSERT INTO student_grades (name, number_grade, fraction_completed)
    VALUES ("Winsteen", 85, 0.906);
INSERT INTO student_grades (name, number_grade, fraction_completed)
    VALUES ("Wincifer", 66, 0.7054);
INSERT INTO student_grades (name, number_grade, fraction_completed)
    VALUES ("Winster", 76, 0.5013);
INSERT INTO student_grades (name, number_grade, fraction_completed)
    VALUES ("Winstonia", 82, 0.9045);

/** select all of the rows, and display the name, number_grade, and percent_completed, which you can compute by multiplying and rounding the fraction_completed column**/

SELECT name, number_grade, ROUND(fraction_completed * 100) as percent_completed FROM student_grades;

/**The goal is a table that shows how many students have earned which letter_grade. You can output the letter_grade by using CASE with the number_grade column, outputting 'A' for grades > 90, 'B' for grades > 80, 'C' for grades > 70, and 'F' otherwise. Then you can use COUNT with GROUP BY to show the number of students with each of those grades.**/

SELECT COUNT (*), 
    CASE 
        WHEN number_grade > 90 THEN "A"
        WHEN number_grade > 80 THEN "B"
        WHEN number_grade > 70 THEN "C"
        ELSE "F"
    END AS "letter_grade"

FROM student_grades
GROUP BY letter_grade