# bbbb为主键字段或唯一索引字段
    sql = 'INSERT INTO aaaa(bbbb)VALUES(%s);'
    cur.execute(sql % 31)
    conn.commit()

    for i in range(30, 35):
        time.sleep(1)
        try:
            # 当i=31时，这条数据提交不上去，其他数据能正常入库
            cur.execute(sql % i)
        except Exception as e:
            print(e, i)

    conn.commit()