我有2个表，并且试图随机选择另一个表中不存在的值，但我无法使其正常工作

Question

ANSWERED TABLE

The following is a questions table. I am trying to select at random a question that has not already been answered and so does not exist in the answered_questions table. The following query includes values that already exist in questions_answered

QUESTIONS TABLE

SELECT * FROM questions WHERE category = 'Random' and question NOT EXISTS (SELECT question FROM answered_questions WHERE game_id=6 and answered_questions.question = questions.question)ORDER BY Rand() LIMIT 10

Answer 1

Not exists donesn't compare with any field

you may use WHERE NOT EXISTS (Subquery)

That will be true if subquery has 0 rows or false if it has 1 or more rows.

You can also use IN like WHERE question in (SELECT question from answers...)

That is true if the subquery returns the same question.