I'm using this expression to calculate date intervals (e.g. to find all records entered within the last 2 weeks):

dateAdded > datediff( now(), '01/01/1904 00:00:00', 'second' ) - (14 * 24 * 60 * 60)

However, it works in some locales but not others. For example, in some languages you need to enter the year as 01.01.1904 or 01-01-1904.

How can I avoid this problem with how the date part separators differ between locales?