# 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

`STD ( expression )`

### Window Function

`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.

A double.

## Examples

```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

`SELECT STD(yearly_total) FROM player_scores;`
``````+-------------------+
| STD(yearly_total) |
+-------------------+
|         57.083158 |
+-------------------+``````

### Window Function

`SELECT player_name, yearly_total, ROUND(std(yearly_total) OVER (ORDER BY player_name, yearly_total)) as stdFROM player_scoresORDER BY player_name;`
``````+-------------+--------------+------+
| 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 |
+-------------+--------------+------+``````