In order to get a the timestamp value before or after certain hours from the current timestamp, I would use the **ADDHOUR()** function.
For instance, to get the timestamp 2 hours prior to the current time, I would use the following query in the **VQL shell** of the** Virtual DataPort Administration Tool**:
SELECT ADDHOUR(current_timestamp,-2) from dual();
You can take a look at the [Datetime Processing Functions](https://community.denodo.com/docs/html/browse/latest/en/vdp/vql/appendix/syntax_of_condition_functions/date_processing_functions) section of the Virtual DataPort VQL Guide for more information.
Hope this helps!