How to add dates to psql dev data code example

Example 1: today minus 15 days postgresql

--yesterday
SELECT NOW() - INTERVAL '1 DAY';

--Unrelated to the question, but PostgreSQL also supports some shortcuts:
SELECT 'yesterday'::TIMESTAMP, 'tomorrow'::TIMESTAMP, 'allballs'::TIME;

Example 2: substract variable amount of minutes from timestamp postgresql

SELECT p.date_time + number_of_seconds * INTERVAL '1 second'
    FROM photo p 
    WHERE p.id = 1;