使用wpf c＃在访问数据库中插入字符串，日期和备忘录值(Insert string, date and memo value in access database using wpf c#)

 我有4个控件。 一个是参考号，日期，主题和正文。 引用号和主题是msaccess中长度为255个字符的文本字段。 正文字段是备忘录字段。 问题是当我尝试使用参数函数将值插入表中时，我在SQL命令文本中仅采用备注字段，命令功能成功执行。 
 
 但是，只要我包含任何其他字段，我就会收到错误“字段太小而无法接受您输入的数据量。请尝试插入或粘贴较少的数据。” 任何人都可以帮我解决这个错误吗？ 
 
 编码如下： 
 
if (btnNew.Content.Equals("_New"))
{
    btnNew.Content = "_Save";

    Clear_Contents();

    dtpDate.Focus();

    btnMod.IsEnabled = false;

    btnDel.IsEnabled = false;

   btnPrint.IsEnabled = false;

}

else

        {

            OleDbConnection conn = DBConnection.getDBConnection();

            OleDbCommand command = conn.CreateCommand();

            string rtfText;

            TextRange richText = new TextRange(txtBody.Document.ContentStart,txtBody.Document.ContentEnd);

            using (MemoryStream ms = new MemoryStream())

            {

                richText.Save(ms, DataFormats.Rtf);

                rtfText = Encoding.ASCII.GetString(ms.ToArray());

            }

            try
            {
                command.Parameters.Add("@body", OleDbType.LongVarChar).Value=rtfText;
              command.Parameters.Add("@refno",OleDbType.VarChar,255).Value=txtPCode.Text;
                command.CommandText = "insert into letter_master(total_ref,let_body)values (@refno,@body)";
                conn.Open();
                command.ExecuteNonQuery();
                conn.Close();
                MessageBox.Show("Record Saved Successfully !!!", DBConnection.Comp_Name, MessageBoxButton.OK, MessageBoxImage.Information);
            }                
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

        }

I have 4 controls. One is reference no, date, subject and body. reference no and subject are text fields in msaccess with 255 characters length. Body field is memo field. Problem is when I try to insert values into the table using parameter function and I take only memo field in my SQL commandText the command function is executed successfully.
 
But as soon as I include any other field I start getting error "The field is too small to accept the amount of data you entered. Try inserting or pasting less data." Can anybody help me how to solve this error?
 
Coding is as follows :
 
if (btnNew.Content.Equals("_New"))
{
    btnNew.Content = "_Save";

    Clear_Contents();

    dtpDate.Focus();

    btnMod.IsEnabled = false;

    btnDel.IsEnabled = false;

   btnPrint.IsEnabled = false;

}

else

        {

            OleDbConnection conn = DBConnection.getDBConnection();

            OleDbCommand command = conn.CreateCommand();

            string rtfText;

            TextRange richText = new TextRange(txtBody.Document.ContentStart,txtBody.Document.ContentEnd);

            using (MemoryStream ms = new MemoryStream())

            {

                richText.Save(ms, DataFormats.Rtf);

                rtfText = Encoding.ASCII.GetString(ms.ToArray());

            }

            try
            {
                command.Parameters.Add("@body", OleDbType.LongVarChar).Value=rtfText;
              command.Parameters.Add("@refno",OleDbType.VarChar,255).Value=txtPCode.Text;
                command.CommandText = "insert into letter_master(total_ref,let_body)values (@refno,@body)";
                conn.Open();
                command.ExecuteNonQuery();
                conn.Close();
                MessageBox.Show("Record Saved Successfully !!!", DBConnection.Comp_Name, MessageBoxButton.OK, MessageBoxImage.Information);
            }                
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

        }

原文：https://stackoverflow.com/questions/23567737