AVG

Returns the average of numeric values.

Syntax

-- As an aggregate
AVG( expr )

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

Arguments

Parameter	Description
expr	Numeric expression

Returns

Return type is dependant on the argument.

• For TINYINT, SMALLINT and INT, the return type is INT.

• For BIGINT, the return type is BIGINT.

• For REAL, the return type is REAL

• For DOUBLE, rhe return type is DOUBLE

Notes

• NULL values are ignored

• AVG relies on calculating the sum, which can very quickly overflow on large data sets. If the sum is over 2³¹ for example, up-cast to a larger type like BIGINT: AVG(expr :: BIGINT)

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 average

t=> SELECT AVG("Age") FROM nba;
avg
---
26

Note

The return type is the same as the input type. To get a fractional result, cast the argument:

t=> SELECT AVG("Age" :: REAL) FROM nba;
avg
-------
26.9387

Combine AVG with other aggregates

t=> SELECT "Age", AVG("Salary") as "Average salary", COUNT(*) as "Number of players" FROM nba GROUP BY 1;
Age | Average salary | Number of players
----+----------------+------------------
 19 |        1930440 |                 2
 20 |        2725790 |                19
 21 |        2067379 |                19
 22 |        2357963 |                26
 23 |        2034746 |                41
 24 |        3785300 |                47
 25 |        3930867 |                45
 26 |        6866566 |                36
 27 |        6676741 |                41
 28 |        5110188 |                31
 29 |        6224177 |                28
 30 |        7061858 |                31
 31 |        8511396 |                22
 32 |        7716958 |                13
 33 |        3930739 |                14
 34 |        7606030 |                10
 35 |        3461739 |                 9
 36 |        2238119 |                10
 37 |       12777778 |                 4
 38 |        1840041 |                 4
 39 |        2517872 |                 2
 40 |        4666916 |                 3