Csharp: Linq Query

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165

/// <summary>         /// Linq 连接查询         /// Geovin Du         /// 涂聚文         /// https://docs.microsoft.com/en-us/dotnet/csharp/linq/perform-inner-joins         /// </summary>         /// <param name="confirmed"></param>         /// <param name="deaths"></param>         /// <param name="recovered"></param>         /// <returns></returns>         public List<HistoryList> getUnionNumber(List<History> confirmed, List<History> deaths, List<History> recovered)         {             List<HistoryList> list = new List<HistoryList>();                 if (recovered.Count > 0)             {                 HistoryList newinfo = null;                 //1 种方法                 var newinfto = (from d in confirmed                                 join c in deaths on d.datename equals c.datename                                 join s in recovered on c.datename equals s.datename                                 select new                                 {                                     datename = d.datename,//                                     numberConfirmed = d.number,//                                     numberDeaths = c.number, //                                     numberRecovered = s.number  //                                 }).ToList();                 int k = 1;                 foreach (var ownerAndDu in newinfto)                 {                     newinfo = new HistoryList();                     newinfo.Id = k;                     newinfo.datename = ownerAndDu.datename;                     newinfo.numberConfirmed = ownerAndDu.numberConfirmed;                     newinfo.numberDeaths = ownerAndDu.numberDeaths;                     newinfo.numberRecovered = ownerAndDu.numberRecovered;                     k++;                     list.Add(newinfo);                 }                              }             else             {                 HistoryList newinfo = null;                 //1 种方法                 var newinfto = from d in confirmed                                join c in deaths on d.datename equals c.datename                                select new                                {                                    datename = d.datename,                                    numberConfirmed = d.number,                                    numberDeaths = c.number                             };                 int k = 1;                   foreach (var ownerAndDu in newinfto)                 {                     newinfo = new HistoryList();                     newinfo.Id = k;                     newinfo.datename = ownerAndDu.datename;                     newinfo.numberConfirmed = ownerAndDu.numberConfirmed;                     newinfo.numberDeaths = ownerAndDu.numberDeaths;                     k++;                     list.Add(newinfo);                 }               }   #region             //for (int i = 0; i < confirmed.Count; i++)             //{               //    HistoryList newinfo = null;             //    if (recovered.Count > 0)             //    {                                         //        //var ss1 =confirmed.Join(deaths, p => p.datename, r => r.datename, (p, r) => p).OrderByDescending(p => p.datename).ToList();             //        //2 种方法             //        if (confirmed[i].datename == deaths[i].datename && confirmed[i].datename == recovered[i].datename)             //        {             //            newinfo = new HistoryList();             //            newinfo.datename = confirmed[i].datename;             //            newinfo.numberConfirmed = confirmed[i].number;             //            newinfo.numberDeaths = deaths[i].number;             //            newinfo.numberRecovered = recovered[i].number;             //            list.Add(newinfo);             //        }                               //    }             //    else             //    {                //        //2 种方法             //        if (confirmed[i].datename == deaths[i].datename)             //        {             //            newinfo = new HistoryList();             //            newinfo.datename = confirmed[i].datename;             //            newinfo.numberConfirmed = confirmed[i].number;             //            newinfo.numberDeaths = deaths[i].number;             //            list.Add(newinfo);             //        }             //    } #endregion                             return list;           }         /// <summary>         ///         /// </summary>         /// <param name="sender"></param>         /// <param name="e"></param>         protected void Page_Load(object sender, EventArgs e)         {             try             {                 if (!IsPostBack)                 {                     id = Request.QueryString["Id"];                     type = Request.QueryString["type"];                     country = Request.QueryString["country"];                     province = Request.QueryString["province"];                     Response.Write("Value:"+id + "," + type+","+country+","+province);                     change(int.Parse(type));                     List<Location> lodea = col.deaths.locations.Where(x => x.country == country && x.province==province).ToList();                     //List<Location> lodea = dea.locations.Where(x => x.country == "US").ToList();                     //List<Location> locir = conf.locations.Where(x => x.country == "US").ToList();                     List<Location> locir = col.confirmed.locations.Where(x => x.country == country && x.province == province).ToList();                     // List<Location> lorec = recov.locations.Where(x => x.country == "US").ToList();                     List<Location> lorec = col.recovered.locations.Where(x => x.country == country && x.province == province).ToList();                     //in                     var geovindu = from geovi in col.recovered.locations                                    where (new string[] { "china", "chile", "Canada" }).Contains(geovi.country)                                    select geovi;                       List<History> hidea = lodea[0].history;  // dea.locations.Where(x => x.country == "Yemen").ToList().Where(x => x.history.All).ToList();                     List<History> hicor = locir[0].history;                     List<History> hirec=new List<History>();                     if(lorec.Count>0)                     {                        hirec = lorec[0].history;                     }                                             List<HistoryList> uniolist = new List<HistoryList>();                     uniolist = getUnionNumber(hicor, hidea, hirec);                     //分页查询                     var geovin = (from du in uniolist                                   where du.Id > 10                                   orderby du.Id descending                                   select du).Skip(10).Take(10); //取第11条到第20条数据                                   this.GridView1.DataSource = uniolist;                     this.GridView1.DataBind();                     }               }             catch (Exception ex)             {                 Response.Write(ex.Message.ToString());             }         }     }

　　数据来源测试： https://coronavirus-tracker-api.herokuapp.com/all