c# - 为什么不能在一种方法中调用两次 OpenConnection()？

Question

为什么我不能在一种方法中调用 OpenConnection() 两次？当我调用它时，会出现此错误：

连接已经打开。

SelectDisPatient()我在和中调用它两次Count()。请参阅我的代码for (int index = 0; index < Count(); index++)

这种方法SelectDisPatient：

public void SelectDisPatient(FrmVIRGO frm)
{
   string query = "SELECT id_pasien FROM tb_patient_information ";
   if (this.OpenConnection() == true)
   { //Create Command
      MySqlCommand cmd = new MySqlCommand(query, connection);
      //Create a data reader and Execute the command
      MySqlDataReader dataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
      if (dataReader.HasRows)
      {
         for (int index = 0; index < Count(); index++)
         dataReader.Read();
         frm.tbName.Text = dataReader[0].ToString(); 
      } 
         //close Data Reader
         dataReader.Close();

         //close Connection
         this.CloseConnection();

    }
 }

这种Count()方法：

public int Count()
{
   string query = "SELECT Count(*) FROM tb_patient_information";
   int Count = -1;

   //Open Connection
   if (this.OpenConnection() == true)
   {
      //Create Mysql Command
      MySqlCommand cmd = new MySqlCommand(query, connection);

      //ExecuteScalar will return one value
      Count = int.Parse(cmd.ExecuteScalar()+"");

      //close Connection
      this.CloseConnection();

      return Count;
    }
    else
    {
       return Count;
    }
 }

(this.OpenConnection() == true)但是当我在方法中删除时，Count()它说我需要关闭连接。

Answer 1

尝试：

public void SelectDisPatient(FrmVIRGO frm)
{
   int count =  Count();
   string query = "SELECT id_pasien FROM tb_patient_information ";
   if (this.OpenConnection() == true)
   { //Create Command
      MySqlCommand cmd = new MySqlCommand(query, connection);
      //Create a data reader and Execute the command
      MySqlDataReader dataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
      if (dataReader.HasRows)
      {
         for (int index = 0; index < count ; index++)
         dataReader.Read();
         frm.tbName.Text = dataReader[0].ToString(); 
      } 
      //close Data Reader
      dataReader.Close();

      //close Connection
      this.CloseConnection();

    }
 }