SQL in a Nutshell, 3rd Edition

PostgreSQL-Supported Functions

This section lists the functions specific to PostgreSQL, with examples and corresponding results.

ABSTIME(timestamp)

Converts the timestamp value to the ABSTIME type. This function is provided for backward compatibility and may be removed in future versions. For example:

SELECT ABSTIME(CURRENT_TIMESTAMP) -> 2003-06-24 00:19:17-07

ACOS(number)

Returns the arccosine of number, ranging from −1 to 1. The result ranges from 0 to π and is expressed in radians. For example:

SELECT ACOS( 0 ) -> 1.570796

AGE(timestamp)

Has the same meaning as AGE(CURRENT_DATE, timestamp).

AGE(timestamp, timestamp)

Returns the time between the two timestamp values. For example:

SELECT AGE( '2003-12-31', CURRENT_TIMESTAMP )
6 mons 7 days 00:34:41.658325

AREA(object)

Returns the area of an item. For example:

SELECT AREA( BOX '((0,0),(1,1))' ) -> 1

ARRAY_APPEND(array, element)

Returns the result of appending element to array. For example:

SELECT ARRAY_APPEND(ARRAY[1,2], 3) -> {1,2,3}

ARRAY_CAT(array1, array2)

Returns the result of appending array2 to array1. For example:

SELECT ARRAY_CAT(ARRAY[1,2], ARRAY[3,4]) -> {1,2,3,4}

ARRAY_DIMS(array)

Returns the dimensions of array. For example:

SELECT ARRAY_DIMS(ARRAY[1,2]) -> '[1:2]'

ARRAY_LOWER(array, i)

Returns the lower bound of the dimension i of array. For example:

SELECT ARRAY_LOWER(ARRAY[1,2], 1) -> 1

ARRAY_PREPEND(i, array)

Returns the result of prepending i to array. For example:

SELECT ARRAY_PREPEND(0, ARRAY[1,2]) -> {0,1,2}

ARRAY_TO_STRING(array, delimiter ...