Useful packages to work with plsql on Oracle Apex
Find the last business day before the given date
function get_previous_business_day ( p_date date ) return date;
Add a specific amount of time to a given date
function add_time (
p_date date,
p_days number default null,
p_hours number default null,
p_minutes number default null,
p_seconds number default null
) return date;