I'm trying to calculate an expiration date by adding the number of days onto the start date. i.e. select start_date + number_of_days from blah;
create table blah (start_date timestamp, number_of_days integer); insert into blah values (current_timestamp, 25); select start_date + number_of_days from blah;
The error I get is:
ERROR: operator does not exist: timestamp without time zone + integer HINT: No operator matches the given name and argument type(s). You may need to add explicit type casts.
But according to http://www.postgresql.org/docs/8.1/static/functions-datetime.html the + operator should support integers and treat them as days ( date '2001-09-28' + integer '7'). Obviously typing a constant into the query is a lot different from using the value of a column, but I would have thought it would work.
What is the correct way to make this calculation?
Use:
select start_date + (cast(number_of_days as text) || ' days')::interval from blah