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" text,
   "Team" text,
   "Number" tinyint,
   "Position" text),
   "Age" tinyint,
   "Height" text,
   "Weight" real,
   "College" text,
   "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