Question

    OleDbConnection baglanti = 
        new OleDbConnection("connect");
    OleDbCommand komut = new OleDbCommand();
    OleDbDataReader dr;
    DataSet ds = new DataSet();
    OleDbDataAdapter da = new OleDbDataAdapter();
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        if(textBox1.Text=="" || textBox2.Text=="" || textBox3.Text=="" || maskedTextBox1.Text=="" || dateTimePicker1.Text=="" || maskedTextBox2.Text=="" || textBox6.Text=="")
        {
            MessageBox.Show("Lütfen Boş alanları doldurunuz !!");
        }
        else
        {
            baglanti.Open();
            komut.Connection = baglanti;
            komut.CommandText=("Select TcKimlik from Hasta");
            dr = komut.ExecuteReader();
            while(dr.Read())
            {
                if(dr["TcKimlik"].ToString()==textBox1.Text.ToString())
                {
                    MessageBox.Show("aaaaa");
                }
                else
                {
                    komut.CommandText = ("insert into Hasta (TcKimlik,h_adı,h_soyadı,tel_no,ran_tar,ran_saati,sikayet_nedeni) values('" + textBox1.Text.ToString() + "','" + textBox2.Text.ToString() + "','" + textBox3.Text.ToString() + "','" + maskedTextBox1.Text.ToString() + "','" + dateTimePicker1.Text.ToString() + "','" + maskedTextBox2.Text.ToString() + "','" + textBox6.Text.ToString() + "')");
                    komut.ExecuteNonQuery();
                    MessageBox.Show("Kayıt Başarı İle Tamamlandı", "Kayıt Başarılı", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);


                }

            }
            baglanti.Close();
            textBox1.Clear();
            textBox2.Clear();
            textBox3.Clear();
            maskedTextBox1.Clear();
            maskedTextBox2.Clear();
            textBox6.Clear();


        }
    }

我尝试了很多方法，但我无法找到解决方案。如果我在注册数据之前检查数据或生成dr.Close()，我可以保存数据，但之后出现错误，因为我过早地关闭了数据读取器。我想检查数据库中的数据，但是我收到如下错误。

与此命令相关联，已经有一个应该首先关闭的显式DataReader。

Answer 1

您的代码问题是您正在利用Command对象一次执行reading and inserting条记录。

您需要逐个执行操作，不能同时执行这两项操作。所以你的代码应该是这样的

using (OleDbconnection connection = new OleDbconnection (ConnectionString))
{
   connection.Open();
   OleDbCommand select = new OleDbCommand("..selecte query",connection);
   OleDbDataReader reader = select.ExecuteReader();

   if (reader.HasRows)
   {
      while (reader.Read())
      {
         //read data you want 

        //you might not need another connection , but i added to seperate it , you can reuse connection you created and perfrom update 
        using(OleDbconnection connection1 = new OleDbconnection (ConnectionString))
           {
               OleDbCommand insert= new OleDbCommand ("..insertquery", connection1);
            insert.ExecuteNonQuery();
           }
         }
      }

      reader.Close();
   }
}

你可以使用命令对象来执行多个任务，但它应该是一个一个，例如

//first complete reading and close reader 
//second do insert operation complete it 
//third do update operation

还有一个建议使用Parameter，因为您的插入查询是针对 sql injection 攻击打开的，如果您使用参数化查询可以解决该问题

DataReader与此命令错误相关联

1 个答案: