gistfile1.sql

UPDATE prepaid_pack p
INNER JOIN booking_detail bd
    ON bd.pack_id = p.pack_id AND bd.related_pack_id = p.pack_id
SET first_used_date = (
    SELECT MIN(booked_date) 
    FROM booking_detail 
    WHERE pack_id = p.pack_id AND related_pack_id = p.pack_id
)
WHERE p.ad_type != 'subscription'