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 returnsNULL
.
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
):
Name | Team | Number | Position | Age | Height | Weight | College | Salary |
---|---|---|---|---|---|---|---|---|
Avery Bradley | Boston Celtics | 0.0 | PG | 25.0 | 6-2 | 180.0 | Texas | 7730337.0 |
Jae Crowder | Boston Celtics | 99.0 | SF | 25.0 | 6-6 | 235.0 | Marquette | 6796117.0 |
John Holland | Boston Celtics | 30.0 | SG | 27.0 | 6-5 | 205.0 | Boston University | |
R.J. Hunter | Boston Celtics | 28.0 | SG | 22.0 | 6-5 | 185.0 | Georgia State | 1148640.0 |
Jonas Jerebko | Boston Celtics | 8.0 | PF | 29.0 | 6-10 | 231.0 | 5000000.0 | |
Amir Johnson | Boston Celtics | 90.0 | PF | 29.0 | 6-9 | 240.0 | 12000000.0 | |
Jordan Mickey | Boston Celtics | 55.0 | PF | 21.0 | 6-8 | 235.0 | LSU | 1170960.0 |
Kelly Olynyk | Boston Celtics | 41.0 | C | 25.0 | 7-0 | 238.0 | Gonzaga | 2165160.0 |
Terry Rozier | Boston Celtics | 12.0 | PG | 22.0 | 6-2 | 190.0 | Louisville | 1824360.0 |
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