• SELECT student_id, cnt = COUNT(subject_id)

    FROM #student_details

    GROUP BY student_id

    HAVING COUNT(subject_id) > 1;

    Since this is most likely a homework assignment of some sorts, make sure you at least understand the solution given.

    Need an answer? No, you need a question
    My blog at https://sqlkover.com.
    MCSE Business Intelligence - Microsoft Data Platform MVP