急求源代码

Question

有没有人可以帮俺一下呢！俺以前没有用过C#现在公司让用C#做一个用户管理系统，就是简单的实现用户的“增，删，改，查”四项功能即可，最最简单的都可以！求各位大侠帮帮忙吧！！非常感谢！！

Answer 1

using System;
using System.Collections.Generic;
using System.Text;
using System.Data.SqlClient;namespace MyQQ
{
    class DBHelper
    {
        //数据库连接字符串
        public static string connString = "Data Source=.; Initial Catalog=MyQQ; User ID=sa";
        //连接数据库
        public static SqlConnection connection = new SqlConnection(connString);
    }
}

Answer 2

 #region //统计返回单个结果CountInfo(string sql)
        public static int CountInfo(string sql)
        {
            int addFriendNum=-1;
            try
            {
                SqlCommand command = new SqlCommand(sql, DBHelper.connection);                                   //声明SqlCommand对象
                DBHelper.connection.Open();                                            //打开连接
                addFriendNum = (int)command.ExecuteScalar();//执行添加好友
            }
            catch (Exception)
            {
                MessageBox.Show("数据库连接出错!请稍后重试！","提示");
            }
            finally {
                DBHelper.connection.Close();
               
            }
            return addFriendNum;
        }
        #endregion
        #region  //执行增删改信息返回受影响的行数UnSelectInfo(string sql)
       public  static int UnSelectInfo(string sql)
        {
            int addFriendNum=-1;
            try
            {
            SqlCommand command = new SqlCommand(sql, DBHelper.connection);                                   //声明SqlCommand对象
            DBHelper.connection.Open();                                            //打开连接
            addFriendNum = command.ExecuteNonQuery();//执行添加好友
            }
            catch (Exception)
            {
                MessageBox.Show("数据库连接出错!请稍后重试！","提示");
            }
            finally {
                DBHelper.connection.Close(); 
            }
            return addFriendNum;
        }
          #endregion

Answer 3

using System; 
using System.Collections.Generic; 
using System.Text; 
using System.Data.SqlClient; namespace MyQQ 
{ 
    class DBHelper 
    { 
        //数据库连接字符串 
        public static string connString = "Data Source=.; Initial Catalog=MyQQ; User ID=sa"; 
        //连接数据库 
        public static SqlConnection connection = new SqlConnection(connString); 
    } 
}#region //统计返回单个结果CountInfo(string sql) 
        public static int CountInfo(string sql) 
        { 
            int addFriendNum=-1; 
            try 
            { 
                SqlCommand command = new SqlCommand(sql, DBHelper.connection);                                  //声明SqlCommand对象 
                DBHelper.connection.Open();                                            //打开连接 
                addFriendNum = (int)command.ExecuteScalar();//执行添加好友 
            } 
            catch (Exception) 
            { 
                MessageBox.Show("数据库连接出错!请稍后重试！","提示"); 
            } 
            finally { 
                DBHelper.connection.Close(); 
              
            } 
            return addFriendNum; 
        } 
        #endregion 
        #region  //执行增删改信息返回受影响的行数UnSelectInfo(string sql) 
      public  static int UnSelectInfo(string sql) 
        { 
            int addFriendNum=-1; 
            try 
            { 
            SqlCommand command = new SqlCommand(sql, DBHelper.connection);                                  //声明SqlCommand对象 
            DBHelper.connection.Open();                                            //打开连接 
            addFriendNum = command.ExecuteNonQuery();//执行添加好友 
            } 
            catch (Exception) 
            { 
                MessageBox.Show("数据库连接出错!请稍后重试！","提示"); 
            } 
            finally { 
                DBHelper.connection.Close(); 
            } 
            return addFriendNum; 
        } 
          #endregion