string conn_str = @"Data Source=(local);Initial Catalog=数据库名;UserID=用户名;Password=密码";
            string show_str = string.Empty;
            using (SqlConnection conn = new SqlConnection(conn_str))
            {
                conn.Open();
                string sql = string.Format("select * from Table where 序号='{0}'",this.textBox1.Text.Trim());
                using (SqlCommand com = new SqlCommand(sql,conn))
                {
                    SqlDataReader dr = com.ExecuteReader();
                    while (dr.Read())
                    {
                        show_str = string.Format("{0} {1} {2} {3}",dr[0].ToString(),dr[1].ToString(),dr[2].ToString(),dr[3].ToString());
                    }
                    dr.Close();
                    dr.Dispose();
                }
            }
            this.textBox2.Text = show_str;//显示