Number of days between dates

Help please! How can I count the number of days between dates using custom column?

In spreadsheet, I would just say =(TODAY()-'last_order_date'!A2) then it will return the number of days between dates once formatted to number.

In Metabase SQL, I would write:
DATE_PART('day', CURRENT_DATE - "public"."customer"."last_order_date").

How can I have the same result using the Question and Custom Column feature in Metabase?