Re: Passing a dynamic interval to generate_series()

Igal Sapir <igal@lucee.org> writes:
> But this throws an error (SQL Error [42601]: ERROR: syntax error at or near
> "'1 '"):

> SELECT generate_series(
>     date_trunc('month', current_date),
>     date_trunc('month', current_date + interval '7 month'),
>     interval ('1 ' || 'month')::interval
> )

You're overthinking it.

SELECT generate_series(
    date_trunc('month', current_date),
    date_trunc('month', current_date + interval '7 month'),
    ('1 ' || 'month')::interval
);
    generate_series
------------------------
 2024-06-01 00:00:00-04
 2024-07-01 00:00:00-04
 2024-08-01 00:00:00-04
 2024-09-01 00:00:00-04
 2024-10-01 00:00:00-04
 2024-11-01 00:00:00-04
 2024-12-01 00:00:00-05
 2025-01-01 00:00:00-05
(8 rows)

It might help to read this:

https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-CONSTANTS-GENERIC

and to experiment with what you get from the constituent elements
of what you tried, rather than trying to guess what they are from
generate_series's behavior.  For example,

select (interval '1 ');
 interval
----------
 00:00:01
(1 row)

select (interval '1 ' || 'month');
   ?column?
---------------
 00:00:01month
(1 row)

            regards, tom lane