my %dayhash = (0 => 'Sonntag',
   1 => 'Montag',
   2 => 'Dienstag',
   3 => 'Mittwoch',
   4 => 'Donnerstag',
   5 => 'Freitag',
   6 => 'Samstag');

while($ref = $sth->fetchrow_hashref()) { 
[...]
  my ($tsec,$tmin,$thour,$tmday,$tmon,$tyear,$twday,$tyday,$tisdst) = localtime($ref->{'time'});
  $twday = $dayhash{$twday};
[...]
}