# STD

Calculates the population standard deviation value from a set of numbers.

`STD` has synonyms `STDDEV` and `STDDEV_POP` which are equivalent.

May be used as a window function.

## Syntax

`STD` returns NULL if there are not matching rows.

## Aggregate Function

```sql
STD ( expression )
```

## Window Function

```sql
STD (col | expr ) OVER ( [PARTITION BY (col | expr )] [ORDER BY (col | expr ) ] )
```

## Arguments

* expression: any expression. This may be a column name, the result of another function, or a math operation.

## Return Type

A double.

## 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 STD(yearly_total) FROM player_scores;


```

```output

+-------------------+
| STD(yearly_total) |
+-------------------+
|         57.083158 |
+-------------------+
```

## Window Function

```sql
SELECT player_name, yearly_total, 
ROUND(std(yearly_total) OVER (ORDER BY player_name, yearly_total)) as std
FROM player_scores
ORDER BY player_name;


```

```output

+-------------+--------------+------+
| player_name | yearly_total | std  |
+-------------+--------------+------+
| 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 |
+-------------+--------------+------+
```

***

Modified at: September 6, 2024

Source: [/cloud/reference/sql-reference/aggregate-functions/std/](https://docs.singlestore.com/cloud/reference/sql-reference/aggregate-functions/std/)

(An index of the documentation is available at /llms.txt)