The following answer uses regexes.

# UK-style
my $in_date = '30-04-2007';
(my $db_date = $in_date) =~ s/(\d\d)-(\d\d)-(\d\d\d\d)/$3-$2-$1/;
(my $pr_date = $db_date) =~ s/(\d\d\d\d)-(\d\d)-(\d\d)/$3-$2-$1/;
print "in: $in_date; db: $db_date; pr: $pr_date\n";
# in: 30-04-2007; db: 2007-04-30; pr: 30-04-2007
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# US-style
my $in_date = '05-14-2007';
(my $db_date = $in_date) =~ s/(\d\d)-(\d\d)-(\d\d\d\d)/$3-$1-$2/;
(my $pr_date = $db_date) =~ s/(\d\d\d\d)-(\d\d)-(\d\d)/$2-$3-$1/;
print "in: $in_date; db: $db_date; pr: $pr_date\n";
# in: 05-14-2007; db: 2007-05-14; pr: 05-14-2007
[download]

Instead of rolling your own, some CPAN modules might help, such as Date::Tiny, Date::Formatter, or Date::Simple. They look promising but I haven't tried them myself.