Do you know in what "zone" your datetime is saved? If not, then there is no way to convert it reliably to UTC.
Usually, if your system needs to be designed to cater for different time zones, you would save the datetime in UTC form, and convert it based on locale...
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"The only true wisdom is in knowing you know nothing"
"O skol'ko nam otkrytiy chudnyh prevnosit microsofta duh!":-D
(So many miracle inventions provided by MS to us...)
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