Question

I have 3 tables in my system: Courses, Scores and Users. Scores is a table which has the test results for each course and each user. So I have the ScoreID, The CourseID the UserID and the Score itself.

I want to show in some page the list of courses that the user didn’t finished yet. So I want it to show all the courses excluding those the user has records in the Scores table (meaning he already has finished it).

How do I exclude the rows from a SELECT statement when certain CourseID and UserID match at the same time?

Answer 1

Assuming that this is for just one user, Mark Bannister’s answer can be simplified a little…

SELECT
  *
FROM
  Courses
WHERE
  NOT EXISTS (SELECT * FROM Scores WHERE CourseID = Courses.CourseID AND UserID = @userID)