Hi Igal: On Mon, 1 Jul 2024 at 01:17, Igal Sapir <igal@xxxxxxxxx> wrote: > I actually did test the expression that I posted, but it might be casting it twice. While your examples that you wrote show 1 month correctly: > SELECT (interval '1 ' || 'month'); > ?column? | > -------------+ > 00:00:01month| No, it does not, try it like this: s=> with a(x) as ( SELECT (interval '1 ' || 'month')) select x, pg_typeof(x) from a; x | pg_typeof ---------------+----------- 00:00:01month | text (1 row) And you'll understand what is happening. Cast to interval has higher priority then concatenation, so you are selecting a 1 second interval, casting it to text, '00:00:01', adding 'month' at end. This can also be noticed because month output would not use ':' and have spaces: s=> with a(x) as ( SELECT '001.00MONTHS'::interval) select x, pg_typeof(x) from a; x | pg_typeof -------+----------- 1 mon | interval (1 row) ( I used fractions, uppercase and no spaces on input to show how interval output normalizes ). Francisco Olarte.