Performing Date/Time Math In HQL?

Question

I'm looking how to perform date/time math within an HQL query. Specifically, how do I add or subtract (x) amount of time from the result of the current_timestamp() function? Or do I have to drop into SQL for this and hope that whatever database is being run supports it?

HQL query example:

FROM RandomThing
WHERE randomTime IS NOT NULL AND
      randomTime >= current_timestamp() AND
      randomTime <= (current_timestamp() + :timeToAdd)

I can define the :timeToSubtract parameter to be any particular unit, though anything bigger than hours would be undesirable, and seconds would be most desirable.

CLARIFICATION: I realize this can be easily done outside of the query. But for philosophical reasons, let's say it's important to use the database server's time, rather than the querying system's time. Practical example: I'm querying an automatic timestamp for all entries made within the last (x) amount of time. Since the timestamp is made by the database system, it is important to also use the database's current time.

Answer 1

Why do you need to do it in the query? Why not just handle it in the java code.

for example:

From RandomThing
Where randomTime is not null and
      randomTime >= :currentTimestamp and
      randomTime <= :maxTimestamp

And then just set the parameters.