DRDS 支持如下聚合函数：
| 函数名 | 描述 |
| AVG() | Return the average value of the argument |
| COUNT() | Return a count of the number of rows returned |
| COUNT(DISTINCT) | Return the count of a number of different values |
| MAX() | Return the maximum value |
| MIN() | Return the minimum value |
| SUM() | Return the sum |
不支持函数列表
与 MySQL5.7 相比，DRDS 暂不支持如下聚合函数：
| 函数名 | 描述 |
| BIT_AND() | Return bitwise AND |
| BIT_OR() | Return bitwise OR |
| BIT_XOR() | Return bitwise XOR |
| GROUP_CONCAT() | Return a concatenated string |
| STD() | Return the population standard deviation |
| STDDEV() | Return the population standard deviation |
| STDDEV_POP() | Return the population standard deviation |
| STDDEV_SAMP() | Return the sample standard deviation |
| VAR_POP() | Return the population standard variance |
| VAR_SAMP() | Return the sample variance |
| VARIANCE() | Return the population standard variance |
