C#用DataTable实现Group by数据统计

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。

DataTable dt = new DataTable();

dt.Columns.AddRange(new DataColumn[] { new DataColumn("name", typeof(string)),

new DataColumn("sex", typeof(string)),

new DataColumn("score", typeof(int)) });

dt.Rows.Add(new object[] { "张三","男",1 });

dt.Rows.Add(new object[] { "张三","男",4 });

dt.Rows.Add(new object[] { "李四","男",100 });

dt.Rows.Add(new object[] { "李四","女",90 });

dt.Rows.Add(new object[] { "王五","女",77 });

DataTable dtResult = dt.Clone();

for (int i = 0; i < dt.Rows.Count; )

{

DataRow dr = dtResult.NewRow();

string name = dt.Rows[i]["name"].ToString();

string sex = dt.Rows[i]["sex"].ToString();

dr["name"] = name;

dr["sex"] = sex;

int score = 0;

//内层也是循环同一个表，当遇到不同的name时跳出内层循环

for (; i < dt.Rows.Count; )

{

if (name == dt.Rows[i]["name"].ToString()&&name == dt.Rows[i]["sex"].ToString())

{

score += Convert.ToInt32(dt.Rows[i]["score"]);

dr["score"] = score;

i++;

}

else

{

break;

}

}

dtResult.Rows.Add(dr);

}

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。

DataTable dt = new DataTable();

dt.Columns.AddRange(new DataColumn[] { new DataColumn("name", typeof(string)),

new DataColumn("sex", typeof(string)),

new DataColumn("score", typeof(int)) });

dt.Rows.Add(new object[] { "张三","男",1 });

dt.Rows.Add(new object[] { "张三","男",4 });

dt.Rows.Add(new object[] { "李四","男",100 });

dt.Rows.Add(new object[] { "李四","女",90 });

dt.Rows.Add(new object[] { "王五","女",77 });

DataTable dtResult = dt.Clone();

DataTable dtName = dt.DefaultView.ToTable(true, "name","sex");

for (int i = 0; i < dtName.Rows.Count; i++)

{

DataRow[] rows = dt.Select("name='" + dtName.Rows[i][0] + "' and sex='" + dtName.Rows[i][1] + "'");

//temp用来存储筛选出来的数据

DataTable temp = dtResult.Clone();

foreach (DataRow row in rows)

{

temp.Rows.Add(row.ItemArray);

}

DataRow dr = dtResult.NewRow();

dr[0] = dtName.Rows[i][0].ToString();

dr[1] = temp.Compute("sum(score)", "");

dtResult.Rows.Add(dr);

}

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);

});

}

收集整理，非原创