...
procedure get_nextCardNumber(t_tohead in number, t_cardnum out number)
as
begin
if t_tohead =  0  then
  select private_reception.SQ_CARDS_NOT_TOHEAD.NEXTVAl
  into t_cardnum
  FROM DUAL;
else
  if t_tohead =  1  then
    select private_reception.SQ_CARDS_TOHEAD.NEXTVAl
    into t_cardnum
    FROM DUAL;
    end if;
end if;
end get_nextCardNumber;
...

public int getNextCardNumber(int tohead) {
OracleConnection conn = new OracleConnection(ConfigurationSettings.AppSettings["ConnectionString"]);
OracleCommand cmd = conn.CreateCommand();

cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = "PRIVATE_RECEPTION.PKG_CARDS.get_nextCardNumber";
cmd.Parameters.Add("t_tohead", OracleType.Number).Value = tohead;
cmd.Parameters.Add(new OracleParameter("t_cardnum", OracleType.Number)).Direction = ParameterDirection.Output;
conn.Open();
int tmp = (int) cmd.ExecuteScalar();
conn.Close();
return tmp;
}

...
DBTIER.sprPackage SPR = new DBTIER.sprPackage();
cardNum = SPR.getNextCardNumber(1);
...