INSERT INTO exam_record_before_2021 (uid,exam_id,start_time,submit_time,score) SELECT uid,exam_id,start_time,submit_time,score FROM exam_record WHERE submit_time<"2021-01-01" AND score IS NOT NULL

INSERT INTO exam_record_before_2021 (uid,exam_id,start_time,submit_time,score) SELECT uid,exam_id,start_time,submit_time,score FROM exam_record WHERE submit_time<"2021-01-01" AND score IS NOT NULL