stddev.md

STDDEV, STDDEV_POP

功能

返回 expr 表达式的标准差

语法

STDDEV(expr)

参数说明

epxr: 被选取的表达式

返回值说明

返回值为数值类型

示例

MySQL > select stddev(scan_rows)
from log_statis
group by datetime;
+---------------------+
| stddev(`scan_rows`) |
+---------------------+
|  2.3736656687790934 |
+---------------------+

MySQL > select stddev_pop(scan_rows)
from log_statis
group by datetime;
+-------------------------+
| stddev_pop(`scan_rows`) |
+-------------------------+
|      2.3722760595994914 |
+-------------------------+