using?System;
using?System.Collections.Generic;
using?System.Linq;
using?System.Text;
using?System.Threading.Tasks;
using?System.Data.SqlClient;
using?System.Data;

namespace?KTV
{
????class?DBHelper
????{
????????public?static?string?connStr?=?@“Data?Source=SISI;Initial?Catalog=KTV;Integrated?Security=True“;
????????static?SqlCommand?cmd?=?null;
????????//獲取sqlconnection對象
?????????static?SqlConnection?Connection{
?????????????get?{
?????????????????return?new?SqlConnection（connStr）;
?????????????}
?????????}
????????///?

????????///?執(zhí)行增刪改返回受影響行
????????///?

????????///?
????????public?static?int?NoQuery（string?sql）?{
????????????SqlConnection?conn?=?Connection;
????????????try
????????????{
????????????????conn.Open（）;
????????????????cmd=?new?SqlCommand（sql?conn）;
????????????????return?cmd.ExecuteNonQuery（）;
????????????}
????????????catch?（Exception?ex）
????????????{
????????????????System.Windows.Forms.MessageBox.Show（ex.Message）;
????????????????return?0;
????????????}
????????????finally?{
????????????????conn.Close（）;
????????????}
????????}
????????///?

????????///?獲取SqlDataReader對象
????????///?

????????///?
????????public?static?SqlDataReader?Reader（string?sql）?{
????????????SqlConnection?conn?=?Connection;
????????????try
????????????{
????????????????conn.Open（）;
????????????????cmd=?new?SqlCommand（sql?conn）;
????????????????return?cmd.ExecuteReader（）;
????????????}
????????????catch?（Exception?ex）
????????????{
????????????????System.Windows.Forms.MessageBox.Show（ex.Message）;
????????????????return?null;
????????????}
????????????finally?{
????????????????conn.Close（）;
????????????}
????????}
????????///?

????????///?獲取DataTable對象
????????///?

????????///?
????????///?
????????public?static?DataTable?Ada（string?sql）
????????{
????????????SqlConnection?conn?=?Connection;
????????????SqlDataAdapter?ada?=?new?SqlDataAdapter（sql?conn）;
????????????DataTable?table?=?new?DataTable（）;
????????????try
????????????{
????????????????ada.Fill（table）;
????????????????return?table;
????????????}
????????????catch?（Exception?ex）?{
????????????????System.Windows.Forms.MessageBox.Show（ex.Message）;
????????????????return?null;
????????????}
????????}
????????///?

????????///?獲取查詢單行單列的結(jié)果
????????///?

????????///?
????????///?
????????public?static?object?Scalar（string?sql）?{
????????????SqlConnection?conn?=?Connection;
????????????try
????????????{
????????????????conn.Open（）;
????????????????cmd?=?new?SqlCommand（sql?conn）;
????????????????return?cmd.ExecuteScalar（）;
????????????}
????????????catch?（Exception?ex）
????????????{
????????????????System.Windows.Forms.MessageBox.Show（ex.Message）;
????????????????return?null;
????????????}
????????????f