use DBI;

my $database = 'somedatabase';  #your system specific
my $hostname = 'localhost';     ##your system specific
my $port     = 3306;            #default mysql port
my $user     = 'someuser';      #your system specific
my $password = 'somepassword';  #your system specific

my $dsn = "DBI:mysql:database=$database;host=$hostname;port=$port"
                or die "DB data set name failed $!\n";
my $dbh = DBI->connect($dsn, $user, $password, {RaiseError => 1}) 
                or die "DB connect failed $!\n";

my $query = $dbh->prepare("SELECT c2.id, c2.name as 'client' 
                          FROM client c2 
                          WHERE level = 50 and status = 1");
$query->execute();
while (my ($id, $name) = $query->fetchrow_array)
{
  print "$id \t $name\n";
}

__END__
To make a parameter a variable, use a placeholder:
my $query = $dbh->prepare("SELECT c2.id, c2.name as 'client' 
                          FROM client c2 
                          WHERE level = ? and status = ?");
$query->execute(50,1);