If you are working in database then you could use some kind of built-in function in your query (few people said it would be faster) -- never done the benchmarking myself.

For example in mysql you can do it this way.

SELECT *,DATEDIFF(NOW(),`YourDateField`) AS `DiffDate` FROM `table` WH
+ERE `x` = 'y'

this will return an additional column for every row containing the dat
+e difference between the current date and the date stored in the data
+base.
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