std

Returns the standard deviation of an expression. Since v2.5.10, this function can also be used as a window function.

Syntax

Haskell

STD(expr)

Parameters

expr: the expression. If it is a table column, it must evaluate to TINYINT, SMALLINT, INT, BIGINT, LARGEINT, FLOAT, DOUBLE, or DECIMAL.

Return value

Returns a DOUBLE value.

Examples

plaintext

MySQL > select * from std_test;
+------+------+
| col0 | col1 |
+------+------+
|    0 |    0 |
|    1 |    2 |
|    2 |    4 |
|    3 |    6 |
|    4 |    8 |
+------+------+

Calculate the standard deviation of col0 and col1.

plaintext

MySQL > select std(col0) as std_of_col0, std(col1) as std_of_col1 from std_test;
+--------------------+--------------------+
| std_of_col0        | std_of_col1        |
+--------------------+--------------------+
| 1.4142135623730951 | 2.8284271247461903 |
+--------------------+--------------------+

keyword

STD