PolarDB-X 1.0支持一個位函數(shù)，即BIT_COUNT()，其返回參數(shù)對應的二進制數(shù)中1的個數(shù)；若參數(shù)為NULL，則返回NULL。

mysql> SELECT BIT_COUNT(29), BIT_COUNT(b'101010');
+--------------+----------------------+
| BIT_COUNT(29) | BIT_COUNT(b'101010') |
+--------------+----------------------+
|            4 |                    3 |
+--------------+----------------------+
1 row in set (0.00 sec)

mysql> SELECT BIT_COUNT(NULL);
+-----------------+
| BIT_COUNT(NULL) |
+-----------------+
|            NULL |
+-----------------+
1 row in set (0.00 sec)