Date

I have a big problem!
I have a table which has a field by date type.
The date format is mm/dd/yyyy.
When I'm doing this select:
select da from a where da='03-31-2002';
the result is :
03-30-2002
03-30-2002
03-30-2002
I repet: only on '03-31-2002'!

What's going on?

Thanks in advance for any help.


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