VAR_POP

Returns the population variance of values.

Note

Aliases to this function include VARP for compatibility.

See also: STDDEV_SAMP

Syntax

-- As an aggregate
VAR_POP( expr )

VARP( expr )

-- As a window function
VAR_POP ( expr ) OVER (
         [ PARTITION BY value_expression [, ...] ]
         [ ORDER BY value_expression [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, ...] ]
         [ frame_clause ]
      )

Arguments

Parameter

Description

expr

Numeric expression

Returns

Returns the population variance with type DOUBLE.

Notes

  • When all rows contain NULL values, the function returns NULL.

Examples

For these examples, assume a table named nba, with the following structure:

CREATE TABLE nba
(
   Name varchar(40),
   Team varchar(40),
   Number tinyint,
   Position varchar(2),
   Age tinyint,
   Height varchar(4),
   Weight real,
   College varchar(40),
   Salary float
 );

Here’s a peek at the table contents (Download nba.csv):

nba.csv

Avery Bradley

Boston Celtics

0

PG

25

2-Jun

180

Texas

7730337

Jae Crowder

Boston Celtics

99

SF

25

6-Jun

235

Marquette

6796117

John Holland

Boston Celtics

30

SG

27

5-Jun

205

Boston University

R.J. Hunter

Boston Celtics

28

SG

22

5-Jun

185

Georgia State

1148640

Jonas Jerebko

Boston Celtics

8

PF

29

10-Jun

231

5000000

Amir Johnson

Boston Celtics

90

PF

29

9-Jun

240

12000000

Jordan Mickey

Boston Celtics

55

PF

21

8-Jun

235

LSU

1170960

Kelly Olynyk

Boston Celtics

41

C

25

Jul-00

238

Gonzaga

2165160

Terry Rozier

Boston Celtics

12

PG

22

2-Jun

190

Louisville

1824360

Simple variance

t=> SELECT "Team", VAR_POP("Age") FROM nba GROUP BY 1 LIMIT 10;
Team                  | var_pop
----------------------+--------
Atlanta Hawks         | 16.6933
Boston Celtics        |  7.5289
Brooklyn Nets         |  8.5067
Charlotte Hornets     |  9.3156
Chicago Bulls         | 16.3733
Cleveland Cavaliers   | 15.8489
Dallas Mavericks      | 12.8622
Denver Nuggets        | 20.9956
Detroit Pistons       | 18.4267
Golden State Warriors | 13.8222

Combine VARP with other aggregates

t=> SELECT "Age", AVG("Salary"), VARP("Salary"), STDDEV_POP("Salary") FROM nba GROUP BY 1;
Age | avg      | var_pop            | stddev_pop
----+----------+--------------------+-------------
 19 |  1930440 |        38966760000 |       197400
 20 |  2725790 | 2162708900784.4473 | 1470615.1437
 21 |  2067379 | 1889747565514.0222 | 1374680.8959
 22 |  2357963 |  2213881715652.018 | 1487911.8642
 23 |  2034746 |  7252716669494.947 | 2693086.8292
 24 |  3785300 | 22559773876347.457 | 4749713.0309
 25 |  3930867 | 20307320771204.332 | 4506364.4739
 26 |  6866566 |   36181973172363.8 |  6015145.316
 27 |  6676741 |  45509106214871.39 | 6746043.7454
 28 |  5110188 |  18012156141081.11 | 4244073.0603
 29 |  6224177 |  22845117042669.63 | 4779656.5821
 30 |  7061858 | 28278583734766.582 | 5317761.1581
 31 |  8511396 |  49074369441838.43 | 7005310.0889
 32 |  7716958 |  51251452013710.28 |  7159011.944
 33 |  3930739 | 17605591394980.715 |  4195901.738
 34 |  7606030 |   28761124471812.6 | 5362939.9094
 35 |  3461739 | 4892789670765.1875 | 2211965.1152
 36 |  2238119 |   2162420877245.64 | 1470517.2142
 37 | 12777778 |  76543207901234.67 | 8748897.5249
 38 |  1840041 |      1679994838499 | 1296146.1486
 39 |  2517872 |   2465360031462.25 |    1570146.5
 40 |  4666916 | 11511680680555.555 | 3392886.7769