8.13. Set Returning Functions

This section describes functions that possibly return more than one row. Currently the only functions in this class are series generating functions, as detailed in Table 8-30.

Table 8-30. Series Generating Functions

Function	Argument Type	Return Type	Description
`generate_series(start, stop)`	`INT` or `BIGINT`	`setof int` or `setof bigint` (same as argument type)	Generate a series of values, from `start` to `stop` with a step size of one.
`generate_series(start, stop, step)`	`INT` or `BIGINT`	`setof int` or `setof bigint` (same as argument type)	Generate a series of values, from `start` to `stop` with a step size of `step`.

When step is positive, zero rows are returned if start is greater than stop. Conversely, when step is negative, zero rows are returned if start is less than stop. Zero rows are also returned for NULL inputs. It is an error for step to be zero. Some examples follow:

select * from generate_series(2,4);
 generate_series
-----------------
               2
               3
               4
(3 rows)

select * from generate_series(5,1,-2);
 generate_series
-----------------
               5
               3
               1
(3 rows)

select * from generate_series(4,3);
 generate_series
-----------------
(0 rows)

select current_date + s.a as dates from generate_series(0,14,7) as s(a);
   dates
------------
 2004-02-05
 2004-02-12
 2004-02-19
(3 rows)