Help Center/ Data Lake Insight/ Spark SQL Syntax Reference/ Built-In Functions/ Aggregate Functions/ stddev_samp
Updated on 2024-08-19 GMT+08:00
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stddev_samp

This function is used to return the sample deviation of a specified column.

Syntax

stddev_samp(col)

Parameters

Table 1 Parameter

Parameter

Mandatory

Description

col

Yes

Columns with a data type of numeric. If the values are of any other type, NULL is returned.

Return Values

The return value is of the DOUBLE type.

Example Code

  • Calculates the sample deviation of all offering inventories (items). An example command is as follows: 
    select stddev_samp(items) from warehouse;

    The command output is as follows:

    +------------+
| _c0        |
+------------+
| 1.342355   |
+------------+
  • When used with group by, it groups all offerings by warehouse (warehourseId) and returns the sample deviation of the offering inventory (items) in the same group. An example command is as follows: 
    select warehourseId, stddev_samp(items) from warehourse group by warehourseId;

    The command output is as follows:

    +------------+------------+
| warehouseId| _c1        |
+------------+------------+
| city1    | 1.23124   |
| city2    | 1.23344   |
| city3    | 1.43425   |
+------------+------------+
Parent topic: Aggregate Functions