//建立一個空表
            DataTable dt = new DataTable();
            dt.Columns.Add("日期", typeof(DateTime));
            dt.Columns.Add("類別", typeof(String));
            dt.Columns.Add("科室", typeof(String));
            dt.Columns.Add("數量", typeof(double));

            //3.通過行框架建立並賦值
            dt.Rows.Add("
 
2020-01-01", "門診","內科",10);
            dt.Rows.Add("2020-01-01", "門診", "外科", 20);
            dt.Rows.Add("2020-01-01", "門診", "骨科", 30);
            dt.Rows.Add("2020-01-01", "住院", "內科病區", 40);
            dt.Rows.Add("2020-01-01", "住院", "小兒病區", 50);
            dt.Rows.Add("2020-01-02", "門診", "內科", 60);
            dt.Rows.Add(
 
"2020-01-02", "門診", "外科", 70);
            dt.Rows.Add("2020-01-02", "住院", "小兒病區", 80);

            var data = dt.AsEnumerable();
            var typeName = "";
            decimal typeSum = 0;
            //一、單柱資料 不需要對比
            //1.按日期彙總數量
            var s = data.GroupBy(r => r["日期"]).Select(g=>new { Name=g.Key,Sum=g.Sum(r=>(double
 
)r["數量"])});
            foreach (var sitem in s.ToList())
            {
                //取出值進行使用
                typeName =sitem.Name.ToString();
                typeSum =Convert.ToDecimal(sitem.Sum.ToString());
            }

            //2.按類別進行彙總
            var s1 = data.GroupBy(r => r["類別"]).Select(g => new { Name = g.Key, Sum = g.Sum(r => (double)r["數量"]) });
            foreach (var s1item in s1.ToList())
            {
                //取出值進行使用
                typeName = s1item.Name.ToString();
                typeSum = Convert.ToDecimal(s1item.Sum.ToString());
            }

            //3.按科室進行彙總
            var s2 = data.GroupBy(r => r["科室"]).Select(g => new { Name = g.Key, Sum = g.Sum(r => (double)r["數量"]) });
            foreach (var s2item in s2.ToList())
            {
                //取出值進行使用
                typeName = s2item.Name.ToString();
                typeSum = Convert.ToDecimal(s2item.Sum.ToString());
            }


            //二、具有對比性質的彙總
            //1.相同時間點下 不同類別數量分別多少
            var t = data.GroupBy(r=> new { 日期=r["日期"],類別= r["類別"] }).Select(g=>new {Name=g.Key.日期,tp = g.Key.類別,Sum=g.Sum(i=>(double)i["數量"]) });


            //2.相同時間節點下 不同科室數量分別多少
            var t1 = data.GroupBy(r => new { 日期 = r["日期"], 科室 = r["科室"] }).Select(g => new { Name = g.Key.日期, tp = g.Key.科室, Sum = g.Sum(i => (double)i["數量"]) });