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" 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
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 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