SQL第十七章项目案例:QQ用户信息管理系统

最新推荐文章于 2025-04-11 15:34:19 发布

倩倩之

最新推荐文章于 2025-04-11 15:34:19 发布

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分类专栏： SQL

本文链接：https://blog.youkuaiyun.com/qq_36074113/article/details/53437036

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这个项目案例展示了如何使用C#和SQL进行QQ用户信息管理，包括获取用户列表、显示用户信息、更新在线天数、插入新用户、更改用户等级和删除用户等操作。通过连接数据库，执行SQL语句来实现用户数据的增删改查。

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

namespace ConsoleApplication1
{
    class DBHandle
    {
        private const string strConn = "Data Source=.;Initial Catalog=QQDB;User ID=admin;Password=bdqn";

        //得到用户列表
        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(CommandBehavior.CloseConnection);
           
          }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
           return null;
           
        }
     }
        //显示用户信息
        public void ShowUserInfo()
        {
            StringBuilder sb = new StringBuilder();
            SqlDataReader reader = GetUserList();
            if (reader == null)
            {
                Console.WriteLine("出现异常");
                return;
            }
            Console.WriteLine("-----------------------------------------------------");
            Console.WriteLine("编号\t\t昵称\t\t等级\t\t邮箱\t\t在线天数");
            while (reader.Read())
            {
                sb.AppendFormat("{0}\t{1}\t{2}\t{3}\t{4}", reader["UserId"], reader["UserName"], reader["LevelName"], reader["Email"], reader["OnLineDay"]);
                Console.WriteLine(sb.ToString());
                sb.Length = 0;
            }
            Console.WriteLine("-----------------------------------------------------");
            reader.Close();
        }

        //更改在线天数
         public int UpdateOnlineDay(int userId, double newOnlineDay)
    {
        try
        {
            SqlConnection conn = new SqlConnection(strConn);
            conn.Open();

            StringBuilder sb = new StringBuilder();
            sb.AppendLine("UPDATE");
            sb.AppendLine("           [UserInfo]");
            sb.AppendLine("  SET");
            sb.AppendLine("          OnLineDay=" + newOnlineDay);
            sb.AppendLine(" WHERE");
            sb.AppendLine("          UserId="+userId);
            
            SqlCommand comm = new SqlCommand(sb.ToString(), conn);
           // Console.WriteLine(sb.ToString());
            return comm.ExecuteNonQuery();
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
            return -1;
        }
    }


  //插入用户信息
         public object InsertUserInfo(string userName, string userPwd, string email)
    {
        SqlConnection conn = new SqlConnection(strConn);
        try
        {
            conn.Open();

            StringBuilder sb = new StringBuilder();
           
            sb.AppendLine(" INSERT INTO");
            sb.AppendLine("          [UserInfo]");
            sb.AppendLine(" VALUES");
            sb.AppendLine("          ('" + userName + "','" + userPwd + "',1,'" + email + "',0);");

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