To get the table field names you can do the following

   my $sth = $dbh->prepare("SELECT * FROM $tablename WHERE 1=0");
   $sth->execute();
   my $fields = $sth->{NAME};
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$dbh should be your connected DB handle
$fields will be an arrayref of the fieldnames
You can also look at the table_info method but check the docs for your DBD driver to see if its supported