>Dion wrote
>How do I decrement the system date by an hour ie current_timestamp - 1
>hour.

I use the standard firebird UDF's, those relevant to your question are:
ADDMILLISECOND
ADDSECOND
ADDHOUR
ADDDAY
ADDMONTH
ADDWEEK
ADDYEAR
So you would use ADDHOUR( current_timestamp, -1) to go back one hour

FWIW
Gary