using System;
using System.Data.OleDb;
using System.Windows.Forms;
using System.Drawing;




        String ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\shn\source\repos\MAILDBSYSTEM\MailDB.accdb";
        OleDbConnection conn;
        OleDbCommand comm;


            string sqlstr = "INSERT INTO USR (USR,TEL,ADDS) VALUES(@USR,@TEL,@ADDS)";
            conn = new OleDbConnection(ConnectionString);
            conn.Open();
            
            try {
                comm = new OleDbCommand(sqlstr, conn);

                OleDbParameter param = comm.CreateParameter();
                param.ParameterName = "@USR3";
                param.OleDbType = OleDbType.VarChar;
                param.Value = textBox1.Text;
                comm.Parameters.Add(param);


                param = comm.CreateParameter();
                param.ParameterName = "@TEL";
                param.OleDbType = OleDbType.VarChar;
                param.Value = textBox2.Text;
                comm.Parameters.Add(param);

                param = comm.CreateParameter();
                param.ParameterName = "@ADDS";
                param.OleDbType = OleDbType.VarChar;
                param.Value = textBox3.Text;
                comm.Parameters.Add(param);

                comm.ExecuteNonQuery();
            }
            catch (Exception ex) {
                MessageBox.Show(ex.Message);
            }
            finally {
                conn.Close();
                conn.Dispose();
            }