Question

How can I change the date by the random number of days in PostgreSQL?

Unfortunately
Generate a random number in the range 1 – 10
solution with trunc doesn’t work:

select date(now()) + (trunc(random()  * 20)) 

results in:

ERROR:  operator does not exist: date + double precision
LÍNEA 1: select date(now()) + (trunc(random()  * 20)) 

Answer 1

select date(now() + trunc(random()  * 20) * '1 day'::interval);

Any existing date column can also be used in place of now()

See: https://www.postgresql.org/docs/current/functions-datetime.html