题解 | #插入记录（二）#

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 year(submit_time) < 2021

这里要注意表exam_record的id列是自增主键列，由于MYSQL提供了一个保证自增主键值正确性的机制–自增锁(一种排他锁)，所以直接INSERT INTO exam_record_before_2021 SELECT * FROM exam_record会导致新表的id列自增成2，因此INSERT时需要排除id列