http://www.cnblogs.com/sydeveloper/archive/2013/03/29/2988669.html
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); }); }
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