VAR_SAMP


var_samp([distinct] expr)

Description

The VAR_SAMP function is used to calculate the sample variance of a set of numerical data. Variance is a statistic that measures the degree of dispersion in a data distribution, reflecting the magnitude of data volatility. By calculating the variance, we can understand the trend and range of data fluctuations.

Parameter Description

expr: Numeric type, can be tinyint, smallint, int, bigint, float, double, or decimal.
distinct (optional): Indicates the calculation of the variance of the set after deduplication. If this parameter is not set, the variance of the set including duplicate values is calculated.

Return Result

Returns a double type value, representing the calculated sample variance.
If the input parameters contain null values, the null values are not included in the calculation.

Usage Example

Calculate the sample variance including duplicate values:


SELECT var_samp(col) FROM VALUES (1), (2), (3), (3), (null) AS tab(col);
+--------------------+
|  `var_samp`(col)   |
+--------------------+
| 0.9166666666666666 |
+--------------------+

Calculate the sample variance after deduplication:


SELECT var_samp(DISTINCT col) FROM VALUES (1), (2), (3), (3), (null) AS tab(col);
+--------------------------+
| `var_samp`(DISTINCT col) |
+--------------------------+
| 1.0                      |
+--------------------------+