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MySQL本身对于位运算有与或非的专属符号 & | ^
在MySQL中提供了bit_and、bit_or、bit_xor的分组函数。
此外MySQL还提供了bit_count函数用以统计二进制中含有1的个数。
mysql> select bit_count(10);
+---------------+
| bit_count(10) |
+---------------+
| 2 |
+---------------+
1 row in set (0.00 sec)
mysql> select bit_count(b'1010');
+--------------------+
| bit_count(b'1010') |
+--------------------+
| 2 |
+--------------------+
1 row in set (0.00 sec)
bit_or：二进制数按位或，bit_and:二进制数按位与，bit_count:统计二进制数1个个数。
应用统计：
mysql> create table visituser(id bigint unsigned not null auto_increment primary key,userid int,brokerid int,y int,m int(2) unsigned zerofill,d int(2) unsigned zerofill);
Query OK, 0 rows affected (0.04 sec)
mysql> insert into visituser(userid,brokerid,y,m,d)values(1000,1,2018,8,1),(1000,2,2018,8,15),(1000,2,2018,8,21),(1002,1,2018,9,1),(1002,1,2018,9,16),(1000,2,2018,9,20),(1000,2,2018,9,25),(1000,2,2018,9,25);
Query OK, 7 rows affected (0.02 sec)
Records: 7 Duplicates: 0 Warnings: 0
select y,m,count(distinct d) days from visit group by y,m;
select y,m,bit_count(bit_or(1<<d)) days from visit group by y,m;
select y,m,userid,brokerid,bit_count(bit_or(1<<d)) days from visituser group by y,m,userid,brokerid;
mysql> select y,m,userid,brokerid,bit_count(bit_or(1<<d)) days from visituser group by y,m,userid,brokerid;
+------+------+--------+----------+------+
| y | m | userid | brokerid | days |
+------+------+--------+----------+------+
| 2018 | 08 | 1000 | 1 | 1 |
| 2018 | 08 | 1000 | 2 | 2 |
| 2018 | 09 | 1002 | 1 | 2 |
| 2018 | 09 | 1000 | 2 | 2 |
+------+------+--------+----------+------+
4 rows in set (0.01 sec)
count(distinct d)
mysql> select y,m,userid,brokerid,count(distinct d) days from visituser group by y,m,userid,brokerid;
mysql> select y,m,userid,brokerid,count(distinct d) days from visituser group by y,m,userid,brokerid;
+------+------+--------+----------+------+
| y | m | userid | brokerid | days |
+------+------+--------+----------+------+
| 2018 | 08 | 1000 | 1 | 1 |
| 2018 | 08 | 1000 | 2 | 2 |
| 2018 | 09 | 1000 | 2 | 2 |
| 2018 | 09 | 1002 | 1 | 2 |
+------+------+--------+----------+------+
4 rows in set (0.03 sec)
解释：
此处针对1<<d 进行解释：这里的计数采取的是位图法，每天有访问就用1表示，02天表示100，23表示1000..(23个0）。
最后经过bit_or按位或后变成10000..(20个0)100,然后用bit_count统计二进制1的个数，非常巧妙。