use huff::WelcomeMessage;
    my $driver = MT::Entry->driver;
    my $dbh = $driver->{dbh}; 
    my $query = "SELECT Name from NGBlogWelcome";
    my $welcome = pop(@{$dbh->selectcol_arrayref($query)});

    $param{welcome} = $welcome;
[download]

if (my $ref = $dbh->selectcol_arrayref($query)) {
  $param{welcome} = pop @$ref;
}
elsif ($DBI::err) {
  die $dbh->errstr;
}
else {
   # nothing returned, but no error?
}
[download]

update: you did notice that selectcol_arrayref returns ALL values in that column, right? I ask because using it to just get the very first row's value will get extremely inefficient fast.
"What should it profit a man, if he should win a flame war, yet lose his cool?"

An alternative to Joost's solution is to set the RaiseError flag to true, causing DBI to throw an exception instead of retuning undef. However, avoiding RaiseError allows you to provide a more meaningful error message.

For example, the following dies with a meaninful error message on error. It also only reads one row since that's all you want.

my $ref = $dbh->selectcol_arrayref($query)
   or die("Unable to fetch blog name: ",
          $DBI::err || "Unknown database error",
          "\n");

$param{welcome} = $ref->[0];
[download]

Update: Added example.