C# ,十七章 项目案例: QQ用户信息管理系统

  测试:

namespace ConsoleApplication1
{
    class Program
    {
        

        static void Main(string[] args)
        {
            UserManager manger = new UserManager();
            manger.Login();
        }
    }
}

DB类 :DB类 :DB类 :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;
namespace ConsoleApplication1
{
    class DBHandle
    {
        string strConn = "Data Source=.;Initial Catalog=QQDB;Integrated Security=True";
        public bool CheckAdminInfo(string userName, string pwd, ref string strMsg)
        {
            SqlConnection conn = new SqlConnection(strConn);
            try
            {
                string strSql = "select count(*) from Admin where LoginId='" + userName + "' and LoginPwd='" + pwd + "'";
                conn.Open();
                SqlCommand comm = new SqlCommand(strSql, conn);
                int iRet = (int)comm.ExecuteScalar();
                if (iRet != 1)
                {
                    strMsg = "输入无效！";
                    return false;
                }
                else
                {
                    return true;
                }



            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                strMsg = "发生异常！";
                return false;
            }
            finally
            {

                conn.Close();
            }
        }
        public SqlDataReader GetUserList()
        {
            try
            {
                SqlConnection conn = new SqlConnection(strConn);
                conn.Open();

                StringBuilder sb = new StringBuilder();
                sb.AppendLine(" SELECT");
                sb.AppendLine("           a.[UserId]");
                sb.AppendLine("          ,a.[UserName]");
                sb.AppendLine("          ,b.[LevelName]");
                sb.AppendLine("          ,a.[Email]");
                sb.AppendLine("          ,a.[OnLineDay]");
                sb.AppendLine(" FROM");
                sb.AppendLine("             [UserInfo] a, [Level] b ");
                sb.AppendLine(" WHERE");
                sb.AppendLine("           a.[LevelId] = b.[LevelId]");
                SqlCommand comm = new SqlCommand(sb.ToString(), conn);

                return comm.ExecuteReader();
            }
            catch (Exception)
            {
                return null;
            }
        }
         
        public SqlDataReader GetUserIdAndOnlineDay()
        {
            try
            {
                SqlConnection conn = new SqlConnectio