如下，可以看到使用后，也统计了null的个数。
mysql> select * from table1; +----------+------------+-----+---------------------+ | name_new | transactor | pid | order_date | +----------+------------+-----+---------------------+ | 1hahha | 1xiaohong | 1 | 2019-08-04 20:45:47 | | 2hahha | 2xiaohong | 2 | 2019-08-04 20:45:57 | | 3hahha | 3xiaohong | 3 | 2019-08-04 20:46:02 | | 4hahha | 4xiaohong | 4 | 2019-08-04 20:46:05 | | 3hahha | bob | 5 | 2019-08-04 20:46:08 | | 3hahha | lee | 6 | 2019-08-04 20:46:12 | | 3hahha | lee | 7 | 2019-08-04 21:56:01 | | 3hahha | lee | 8 | 2019-08-04 21:56:10 | | 3hahha | bob | 9 | 2019-08-04 21:56:18 | | 3hahha | bob | 10 | 2019-08-04 21:56:26 | +----------+------------+-----+---------------------+ 10 rows in set (0.00 sec) mysql> select transactor,count(*) as num from table1 group by transactor; +------------+-----+ | transactor | num | +------------+-----+ | 1xiaohong | 1 | | 2xiaohong | 1 | | 3xiaohong | 1 | | 4xiaohong | 1 | | bob | 3 | | lee | 3 | +------------+-----+ 6 rows in set (0.00 sec) mysql> select transactor,count(*) as num from table1 group by transactor with rollup; +------------+-----+ | transactor | num | +------------+-----+ | 1xiaohong | 1 | | 2xiaohong | 1 | | 3xiaohong | 1 | | 4xiaohong | 1 | | bob | 3 | | lee | 3 | | NULL | 10 | +------------+-----+ 7 rows in set (0.01 sec)