C#用DataTable实现Group by数据统计 -数据天堂

C#用DataTable实现Group by数据统计

# windos 2024-04-03 09:12 0 23 来源：数据天堂

1、用两层循环计算，前提条件是数据已经按分组的列排好序的。

 1 DataTable dt = new DataTable(); 2 dt.Columns.AddRange(new DataColumn[] { new DataColumn("name", typeof(string)), 3 new DataColumn("sex", typeof(string)), 4 new DataColumn("score", typeof(int)) }); 5 dt.Rows.Add(new object[] { "张三","男",1 }); 6 dt.Rows.Add(new object[] { "张三","男",4 }); 7 dt.Rows.Add(new object[] { "李四","男",100 }); 8 dt.Rows.Add(new object[] { "李四","女",90 }); 9 dt.Rows.Add(new object[] { "王五","女",77 });10 DataTable dtResult = dt.Clone();11 for (int i = 0; i < dt.Rows.Count; )12 {13 DataRow dr = dtResult.NewRow();14 string name = dt.Rows[i]["name"].ToString();15 string sex = dt.Rows[i]["sex"].ToString();16 dr["name"] = name;17 dr["sex"] = sex;18 int score = 0;19 //内层也是循环同一个表，当遇到不同的name时跳出内层循环20 for (; i < dt.Rows.Count; )21  {22 if (name == dt.Rows[i]["name"].ToString()&&name == dt.Rows[i]["sex"].ToString())23  {24 score += Convert.ToInt32(dt.Rows[i]["score"]);25 dr["score"] = score;26 i++;27  }28 else29  {30 break;31  }32  }33  dtResult.Rows.Add(dr);34 }35 36 dtResult中的数据即是最终结果。

2、借助DataTable的Compute方法，DataTable中数据不用事先排好序。

 1 DataTable dt = new DataTable(); 2 dt.Columns.AddRange(new DataColumn[] { new DataColumn("name", typeof(string)), 3 new DataColumn("sex", typeof(string)), 4 new DataColumn("score", typeof(int)) }); 5 dt.Rows.Add(new object[] { "张三","男",1 }); 6 dt.Rows.Add(new object[] { "张三","男",4 }); 7 dt.Rows.Add(new object[] { "李四","男",100 }); 8 dt.Rows.Add(new object[] { "李四","女",90 }); 9 dt.Rows.Add(new object[] { "王五","女",77 });10 DataTable dtResult = dt.Clone();11 DataTable dtName = dt.DefaultView.ToTable(true, "name","sex");12 for (int i = 0; i < dtName.Rows.Count; i++)13 {14 DataRow[] rows = dt.Select("name=‘" + dtName.Rows[i][0] + "‘ and sex=‘" + dtName.Rows[i][1] + "‘");15 //temp用来存储筛选出来的数据16 DataTable temp = dtResult.Clone();17 foreach (DataRow row in rows)18  {19  temp.Rows.Add(row.ItemArray);20  }21 22 DataRow dr = dtResult.NewRow();23 dr[0] = dtName.Rows[i][0].ToString();24 dr[1] = temp.Compute("sum(score)", "");25  dtResult.Rows.Add(dr);26 }

3、使用linq to DataTable group by实现

var query = from t in dt.AsEnumerable() group t by new { t1 = t.Field<string>("name"), t2 = t.Field<string>("sex") } into m select new { name = m.Key.t1, sex = m.Key.t2, score = m.Sum(n => n.Field<decimal>("score")) };if (query.ToList().Count > 0){ query.ToList().ForEach(q => { Console.WriteLine(q.name + "," + q.sex + "," + q.score); });}