Relative times

I would like to create a query in Oracle which checks data for the last 4 hours. In Oracle, I know that if I want a relative day, I'd say "Sysdate - 1". But how do I make it go to hours? When I try 'sysdate - 0.17', the query takes forever to run - but it runs well with whole numbers. We're on Oracle 7.3.

Any and all help appreciated. Received on Fri Nov 09 2001 - 20:07:04 CST