select now() from db_root into :t1;
select <whatever you need>, now() - :t1 AS TimeDiff .... etc
..or something like this - I don't have access now to test the exact syntax.
See more here:
http://www.cubrid.org/manual/840/en/SELECT-Overview ([:]identifier : By using the :identifier after TO (or INTO), you can save the data to be retrieved in the ':identifier' variable.)
Hope it helps.
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