Zkuste něco jako
SELECt t1.*
FROM Table1 t1 LEFT JOIN
Table2 t2 ON t1.questionID = t2.questionID
WHERE t2.questionID IS NULL
Zkuste něco jako
SELECt t1.*
FROM Table1 t1 LEFT JOIN
Table2 t2 ON t1.questionID = t2.questionID
WHERE t2.questionID IS NULL