Question

Requirements: I have a table of several thousand questions. Users can view these multiple choice questions and then answer them. Once a question is answered, it should not be shown to the same user again even if he logs in after a while.

Question

How would I go about doing this efficiently? Would Bloom Filters work?

Answer 1

Create a QuestionsAnswered table and join on it in your select. When the user answers a question, insert the question ID and the user ID into the table.

CREATE TABLE QuestionsAnswered (UserID INT, QuestionID INT)

SELECT *
FROM Question
WHERE ID NOT IN (SELECT QuestionID 
                 FROM QuestionsAnswered
                 WHERE UserID = @UserID)

INSERT INTO QuestionsAnswered
(UserID, QuestionID)
VALUES
(@UserID, @QuestionID)