我有一个看起来像这样的无类型DataTable（srcTbl）：
date col_1 col_2 ... col_n
1.3.2010 00:00 12.5 0 ... 100
1.3.2010 01:00 0 0 ... 100
1.3.2010 22:00 0 0 ... 100
1.3.2010 23:00 12.5 0 ... 100
...
31.3.2010 00:00 2 0 ... 100
31.3.2010 01:00 2 0 ... 200
我需要总结按日期分组的行以获得类似的数据表（dstTbl）：
date, col_1 col_2 ... col_n
1.3.2010 15 0 ... 400
...
31.3.2010 4 0 ... 300
这是否可以通过使用LINQ，如果可以的话？
答案 0 :(得分：1)
好的，所以你可以像这样实现它。这是一个工作版本，所以你不应该有太多问题。
DataTable myDataTable = new DataTable();
myDataTable.Columns.Add("Date", typeof(DateTime));
myDataTable.Columns.Add("Col1", typeof(int));
myDataTable.Columns.Add("Col2", typeof(int));
myDataTable.Columns.Add("Col3", typeof(int));
var datarow1 = myDataTable.NewRow();
datarow1.SetField("Date", DateTime.Parse("01/03/09 00:01:00"));
datarow1.SetField("Col1", 12);
datarow1.SetField("Col2", 0);
datarow1.SetField("Col3", 100);
var datarow2 = myDataTable.NewRow();
datarow2.SetField("Date", DateTime.Parse("01/03/09 01:03:00"));
datarow2.SetField("Col1", 12);
datarow2.SetField("Col2", 0);
datarow2.SetField("Col3", 100);
var datarow3 = myDataTable.NewRow();
datarow3.SetField("Date", DateTime.Parse("01/03/09 02:05:00"));
datarow3.SetField("Col1", 0);
datarow3.SetField("Col2", 0);
datarow3.SetField("Col3", 100);
var datarow4 = myDataTable.NewRow();
datarow4.SetField("Date", DateTime.Parse("10/10/09 00:03:00"));
datarow4.SetField("Col1", 2);
datarow4.SetField("Col2", 0);
datarow4.SetField("Col3", 100);
var datarow5 = myDataTable.NewRow();
datarow5.SetField("Date", DateTime.Parse("31/03/09 01:03:00"));
datarow5.SetField("Col1", 2);
datarow5.SetField("Col2", 0);
datarow5.SetField("Col3", 100);
var datarow6 = myDataTable.NewRow();
datarow6.SetField("Date", DateTime.Parse("31/03/09 03:04:00"));
datarow6.SetField("Col1", 2);
datarow6.SetField("Col2", 0);
datarow6.SetField("Col3", 100);
myDataTable.Rows.Add(datarow1);
myDataTable.Rows.Add(datarow2);
myDataTable.Rows.Add(datarow3);
myDataTable.Rows.Add(datarow4);
myDataTable.Rows.Add(datarow5);
myDataTable.Rows.Add(datarow6);
var q = (from t in myDataTable.AsEnumerable()
group t by new {t.Field<DateTime>("Date").Day, t.Field<DateTime>("Date").Month, t.Field<DateTime>("Date").Year}
into temp
select myDataTable.LoadDataRow(
new object[]
{
string.Format("{0}.{1}.{2}", temp.Key.Day, temp.Key.Month, temp.Key.Year),
temp.Sum(r => r.Field<int>("Col1")),
temp.Sum(r => r.Field<int>("Col2")),
temp.Sum(r => r.Field<int>("Col3")),
}, LoadOption.PreserveChanges));
DataTable newTable = q.CopyToDataTable();
var datarow1 = myDataTable.NewRow();
datarow1.SetField("Date", DateTime.Parse("01/03/09 00:01:00"));
datarow1.SetField("Col1", 12);
datarow1.SetField("Col2", 0);
datarow1.SetField("Col3", 100);
var datarow2 = myDataTable.NewRow();
datarow2.SetField("Date", DateTime.Parse("01/03/09 01:03:00"));
datarow2.SetField("Col1", 12);
datarow2.SetField("Col2", 0);
datarow2.SetField("Col3", 100);
var datarow3 = myDataTable.NewRow();
datarow3.SetField("Date", DateTime.Parse("01/03/09 02:05:00"));
datarow3.SetField("Col1", 0);
datarow3.SetField("Col2", 0);
datarow3.SetField("Col3", 100);
var datarow4 = myDataTable.NewRow();
datarow4.SetField("Date", DateTime.Parse("10/10/09 00:03:00"));
datarow4.SetField("Col1", 2);
datarow4.SetField("Col2", 0);
datarow4.SetField("Col3", 100);
var datarow5 = myDataTable.NewRow();
datarow5.SetField("Date", DateTime.Parse("31/03/09 01:03:00"));
datarow5.SetField("Col1", 2);
datarow5.SetField("Col2", 0);
datarow5.SetField("Col3", 100);
var datarow6 = myDataTable.NewRow();
datarow6.SetField("Date", DateTime.Parse("31/03/09 03:04:00"));
datarow6.SetField("Col1", 2);
datarow6.SetField("Col2", 0);
datarow6.SetField("Col3", 100);
myDataTable.Rows.Add(datarow1);
myDataTable.Rows.Add(datarow2);
myDataTable.Rows.Add(datarow3);
myDataTable.Rows.Add(datarow4);
myDataTable.Rows.Add(datarow5);
myDataTable.Rows.Add(datarow6);
var q = (from t in myDataTable.AsEnumerable()
group t by new {t.Field<DateTime>("Date").Day, t.Field<DateTime>("Date").Month, t.Field<DateTime>("Date").Year}
into temp
select myDataTable.LoadDataRow(
new object[]
{
string.Format("{0}.{1}.{2}", temp.Key.Day, temp.Key.Month, temp.Key.Year),
temp.Sum(r => r.Field<int>("Col1")),
temp.Sum(r => r.Field<int>("Col2")),
temp.Sum(r => r.Field<int>("Col3")),
}, LoadOption.PreserveChanges));
DataTable newTable = q.CopyToDataTable();
答案 1 :(得分：0)
我找到了解决问题的方法，但是我必须在for循环中处理每个列。也许有人知道如何放过这个。
public static DataTable HoursToDailySums(DataTable src_tbl)
{
DataTable dst_tbl = src_tbl.Clone();
// handle the dates column
var qry = from row in src_tbl.AsEnumerable()
group row by ((DateTime)row[0]).Date into g
orderby g.Key
select g.Key;
foreach(DateTime date in qry)
{
DataRow new_row = dst_tbl.NewRow();
new_row[0] = date;
dst_tbl.Rows.Add(new_row);
}
// handle all other columns
for (int col = 1; col < dst_tbl.Columns.Count; col++)
{
var sumQry = from row in src_tbl.AsEnumerable()
group row by ((DateTime)row[0]).Date into g
orderby g.Key
select g.Sum(row => row.Field<double>(col));
int row_index = 0;
foreach(double sum in sumQry)
{
dst_tbl.Rows[row_index++][col] = sum;
}
}
return dst_tbl;
}