You cannot use a place holder in the selection list. What may work for you is (untested):

my $sth = $dbh->prepare("SELECT *, DATE_FORMAT(...) as something from 
+cases where caseid = ?");
$sth->execute($x);
while (my $hash = $sth->fetchrow_hashref()) {
    my @row = @$hash{$col, "status", "something"};
    ...
}
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