How to pass part of a parameter in a variable?

Question

SQL

there is xls with odbc connection to postgres and sql-query execution
Some variables if we replace them with ? will be specified when it is executed in a pop-up window, but for "complex" variables such a trick does not work, in particular, it is necessary to clarify the value of the bold font:

WHERE p.saletime > (now() - '<b>10</b> days'::interval)

If it is replaced by ? , then an error occurs (screenshot).
A similar case was with the request:

WHERE un_cg_product.name ilike %?%   AND  erpi_purchase.saletime > (now() - '31 days'::interval)

but such a detour saved there:
un_cg_product.name ilike '%'||?||'%'if done by analogy - (now() - ''||?||' days'::interval)
then

Answer 1

There is nothing to try on yourself, but the following approach with interval multiplication usually works:
(now() - ? * '1 days'::interval)