SQL Server 2019

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CREATE TABLE Course (
  "id" INTEGER PRIMARY KEY,
  "name" VARCHAR(5),
  "course" VARCHAR(7),
  "date" VARCHAR(10),
  "grade" INTEGER
);

INSERT INTO Course
  ("id", "name", "course", "date", "grade")
VALUES
  ('1', 'Jane', 'french', '2016-11-20', '20'),
  ('3', 'CARL', 'french', '2015-09-02', '30'),
  ('4', 'Anna', 'french', '2016-11-20', '25'),
  ('5', 'JON', 'french', '2016-09-02', '56'),
  ('6', 'Linda', 'english', '2016-09-02', '22'),
  ('7', 'TIM', 'english', '2016-11-20', '23'),
  ('8', 'JON', 'english', '2016-11-20', '44');
7 rows affected

SELECT
  c.Course,
  AVG(Grade * 1.0) AvgGrade
FROM Course c
GROUP BY
  c.Course;


Course
AvgGrade


english
29.666666

french
32.750000


SELECT
  c.Course,
  AVG(Count * 1.0) AvgCount
FROM (
    SELECT
      c.Course,
      COUNT(*) Count
    FROM Course c
    GROUP BY
      c.Course,
      c.Date
) c
GROUP BY
  c.Course;


Course
AvgCount


english
1.500000

french
1.333333


SELECT
  c.Course,
  AVG(Count * 1.0) AvgCount,
  SUM(c.TotalGrades) * 1.0 / SUM(Count) AvgGrade
FROM (
    SELECT
      c.Course,
      COUNT(*) Count,
      SUM(c.Grade) TotalGrades
    FROM Course c
    GROUP BY
      c.Course,
      c.Date
) c
GROUP BY
  c.Course;


Course
AvgCount
AvgGrade


english
1.500000
29.666666666666

french
1.333333
32.750000000000