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 T_USR (USR,TEL,ADDS) VALUES(@USR,@TEL,@ADDS)";
            conn = new OleDbConnection(ConnectionString);
            conn.Open();

            try {
                comm = new OleDbCommand(sqlstr, conn);

                List sqlParameters = new List();
                sqlParameters.AddSqlParameter(new OleDbParameter("@USR", OleDbType.VarChar)).Value = textBox1.Text;
                sqlParameters.AddSqlParameter(new OleDbParameter("@TEL", OleDbType.VarChar)).Value = textBox2.Text;
                sqlParameters.AddSqlParameter(new OleDbParameter("@ADDS", OleDbType.VarChar)).Value = textBox3.Text;

                comm.Parameters.AddParams(sqlParameters);
                comm.ExecuteNonQuery();
            }
            catch (Exception ex) {
                MessageBox.Show(ex.Message);
                return;
            }
            finally {
                conn.Close();
                conn.Dispose();
            }
///////////////


    public static class SqlParameterExtension {

        public static OleDbParameter AddSqlParameter(this List list, OleDbParameter parameter) {
            list.Add(parameter);
            return parameter;
        }

        public static void AddParams(this OleDbParameterCollection collection, List list) {
            foreach (OleDbParameter parameter in list) {
                collection.Add(parameter);
            }
        }
    }