Help with DATE conversion based on sessiontimezone, dbtimezone

I would like to convert a date value in a select statement to the session timezone. I know I can use NEW_TIME with the timezone abbreviations, but dbtimezone and sessiontimezone returns offsets (-05:00 for CST etc). not timezone abbreviations. Since I want to adjust the date by the interval
between dbtimezone and sessiontimezone, Iwas thinking something like:

select new_time(old_date,
decode(dbtimezone,'-04:00','EST','-05:00','CST','-06:00','MST','-07:00','PST','-08:00','YST'), decode(sessiontimezone,'-04:00','EST','-05:00','CST','-06:00','MST','-07:00','PST','-08:00','YST'))

but this doesn't seem very elegant, and I don't think very efficient for a large number of records. Any suggestions? Received on Fri Apr 28 2006 - 13:18:06 CDT