You probably want to put the rest of the code in the loop body

I thought that at first, but then I figured his query returns at most one row. Using a loop to fetch one item is very misleading. He should probably have used

my $dbpass = $sth->fetch;
($UIDholder, $LNholder) = @{$dbpass};
...
[download]

or

my $dbpass = $sth->fetch
   or die("Bad data. XXX not found\n");
$sth->fetch
   and die("Bad data. Multiple XXX in table YYY\n");
($UIDholder, $LNholder) = @{$dbpass};
...
[download]