# Table: group
# Columns: id, name
# Values: 1, Admin
#         2, User
#         3, Public

my $sql = 'select * from group';
my $r = $dbh->selectcol_arrayref($sql); # default to first column

# or, if you want the the 'name' column
my @r = @{$dbh->selectcol_arrayref($sql, {Columns=>[2]})}; # we want the 2nd column

# if you know the column name you want in advanced:
my $sql2 = 'select name from group';
my @group_names = @{$dbh->selectcol_arrayref($sql2)};

print Data::Dumper->Dump(
  [$r, \@r, \@group_names],
  [qw(id name group_names)],
);