Important

Self-managed SingleStore will soon transition from version 9.1 RC to version 10. This new semantic versioning scheme will provide SingleStore with finer control over engine and feature releases that were not possible with the current versioning scheme.

In the interim, SingleStore 9.1 RC can be used to preview, evaluate, and provide feedback on the new and upcoming features in SingleStore 10 prior to its general availability. Ahead of this transition, SingleStore 9.0 is recommended for production workloads, which can later be upgraded to SingleStore 10.

STDDEV

Syntax

Aggregate Function

SQL

STDDEV( [ DISTINCT ] <expression>

Window Function & Window Frame Clause

SQL

STDDEV( [DISTINCT ] (col | expr ) OVER ( [ PARTITION BY (col | expr )] [ ORDER BY (col | expr ) [ <window_frame> ] ] )

Arguments

expression: numeric expression

Return Type

Returns the standard deviation of the expression or NULL if there are no matching rows.

Examples

The following table and values were used for the examples:

SQL

CREATE TABLE player_scores(player_name VARCHAR(50), player_id VARCHAR(10),
    1st_qtr_score DECIMAL(5,2), 2nd_qtr_score DECIMAL(5,2),
    3rd_qtr_score DECIMAL(5,2), 4th_qtr_score DECIMAL(5,2),
    yearly_total AS 1st_qtr_score + 2nd_qtr_score + 3rd_qtr_score + 4th_qtr_score PERSISTED DECIMAL(5,2));

INSERT INTO player_scores VALUES
    ('Steve', '119','22.50','72.00', '63.00', '45.00'),
    ('Jack', '432', '90.10', '78.00','88.20', '92.20'),
    ('Jim', '779','75.00', '68.90','55.70', '72.00'),
    ('Eve', '189','91.50', '88.10', '95.00', '94.50'),
    ('Shelia','338', '75.60', '72.00', '81.10', '78.40'),
    ('June', '521', '81.00', '87.30','76.80','82.20'),
    ('Martin', '674','98.80', '95.10', '88.00', '96.40');

Aggregate Function

SQL

SELECT STDDEV(yearly_total) FROM player_scores;

+----------------------+
| STDDEV(yearly_total) |
+----------------------+
|            57.083158 |
+----------------------+

Window Function

SQL

SELECT player_name, yearly_total,
ROUND(stddev(yearly_total) OVER (ORDER BY player_name, yearly_total)) AS stddev
FROM player_scores
ORDER BY player_name;

+-------------+--------------+--------+
| player_name | yearly_total | stddev |
+-------------+--------------+--------+
| Eve         |       369.10 |      0 |
| Jack        |       348.50 |     10 |
| Jim         |       271.60 |     42 |
| June        |       327.30 |     36 |
| Martin      |       378.30 |     38 |
| Shelia      |       307.10 |     37 |
| Steve       |       202.50 |     57 |
+-------------+--------------+--------+

Window Frame Clause

SQL

SELECT player_name, yearly_total,
ROUND(stddev(yearly_total) OVER (ORDER BY player_name, yearly_total ROWS UNBOUNDED PRECEDING)) AS stddev
FROM player_scores
ORDER BY player_name;

+-------------+--------------+--------+
| player_name | yearly_total | stddev |
+-------------+--------------+--------+
| Eve         |       369.10 |      0 |
| Jack        |       348.50 |     10 |
| Jim         |       271.60 |     42 |
| June        |       327.30 |     36 |
| Martin      |       378.30 |     38 |
| Shelia      |       307.10 |     37 |
| Steve       |       202.50 |     57 |
+-------------+--------------+--------+

STDDEV

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Syntax

Aggregate Function

Window Function & Window Frame Clause

Arguments

Return Type

Examples

Aggregate Function

Window Function

Window Frame Clause

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