C#

Fields that are declared volatile are not subject to compiler optimizations that assume access by a single thread

string connectionString = "provider=Microsoft.JET.OLEDB.4.0; " + "data source =" + Dir;
        
string commandString = "Select id,Event from Events";
           
OleDbDataAdapter dataAdapter = new OleDbDataAdapter(commandString, connectionString);
DataSet ds = new DataSet();             
dataAdapter.Fill(ds, "Events");
                                          
DataTable datatable = ds.Tables[0];
DataRow newRow = datatable.NewRow();
newRow["id"] = "aaa";                  
newRow["Event"] = "bbb";

datatable.Rows.Add(newRow);

dataAdapter.Update(ds, "Events");
ds.AcceptChanges();
Application.DoEvents();

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace sts
{
    public partial class Voucher : Form
    {
         SqlConnection cn;
        public Voucher()
        {
            InitializeComponent();
        }
  
        private void btnSave_Click(object sender, EventArgs e)
        {  string connectionString = "Data Source=RYANS-27F187045\\SQLEXPRESS;Initial Catalog=msdb;Integrated Security=sspi";
            cn = new SqlConnection(connectionString);
        
            cn.Open();
            SqlCommand cmd = cn.CreateCommand();
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.CommandText = "insertv";
 
            cmd.Parameters.Add(new SqlParameter("@Id_No", SqlDbType.Int));
            cmd.Parameters["@Id_No"].Value = txtId_No.Text;

            cmd.Parameters.Add(new SqlParameter("@NAME_OF_ACCOUNT", SqlDbType.VarChar, 50));
            cmd.Parameters["@NAME_OF_ACCOUNT"].Value = txtNAME_OF_ACCOUNT.Text;

            cmd.Parameters.Add(new SqlParameter("@QUANTITY", SqlDbType.Float));
            cmd.Parameters["@QUANTITY"].Value = txtQUANTITY.Text;

            cmd.Parameters.Add(new SqlParameter("@PRICE", SqlDbType.Float));
            cmd.Parameters["@PRICE"].Value = txtPRICE.Text;

            
            cmd.Parameters.Add(new SqlParameter("@TOTAL_AMOUNT", SqlDbType.Float));
            cmd.Parameters["@TOTAL_AMOUNT"].Value = txtTOTAL_AMOUNT.Text;
            
           
            cmd.Parameters.Add(new SqlParameter("@DATE", SqlDbType.DateTime));
            cmd.Parameters["@DATE"].Value = txtDATE.Text;
           
            cn.Close();


        }
        private void Voucher_Load(object sender, EventArgs e)
        {
            string connectionString = "Data Source=RYANS-27F187045\\SQLEXPRESS;Initial Catalog=msdb;Integrated Security=sspi";
            cn = new SqlConnection(connectionString);
        }


       

        private void txtVoucherc_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {

        }

        private void txtDATE_TextChanged(object sender, EventArgs e)
        {

        }
        
       
        
    }
}