Converting a date/time to time_t using FxGqlC (or SQL)

The time_t is used in C++ to represent a date/time.  It is expressed in seconds since Januari 1st, 1970.

To get the current date/time as a time_t value, you can run this query in FxGqlC (or SQL):
select datediff(second, '1970-01-01', getutcdate())

You need to use getutcdate() because time_t defines the UTC time.

Or for any arbitrary date/time (in UTC):
select datediff(second, '1970-01-01', '2012-10-18 22:33') 
-- Returns 1350599580

The other way around is also easy: run this query to convert a time_t to a date/time
select dateadd(second, 1234567890, '1970-01-01')
-- Returns 13/02/2009 23:31:30