As Zaxo mentions, your best bet for storing and comparing dates in MySQL is to use a DATE column, however for some problems using an big integer to store the time (seconds since epoch) can be more intuitive:

my $last28days = time - 60*60*24*28;
$sql = "SELECT * FROM TTD WHERE SecSinceEpoch > $last28days";
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It could also mean that I need to brush up on my SQL :-)
YMMV,
Joost.

-- 
Joost       downtime n. The period during which a system
            is error-free and immune from user input.
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