更新：添加了一个新的列，将日期和时间列合并为DateTimeCombined列中的字符串字段，这是一个DateTime字段
那么LINQ应该做的是按名称列分组，并为每个具有最早日期+时间的名称获取行。然后它应该为名称添加行的其余部分。
DataTable init：
dataT = new DataTable();
dataT.Columns.Add("Date", typeof(string));
dataT.Columns.Add("Time", typeof(string));
dataT.Columns.Add("Day", typeof(string));
dataT.Columns.Add("Name", typeof(string));
dataT.Columns.Add("Place", typeof(string));
dataT.Columns.Add("DateTimeCombined", typeof(DateTime));
dataT.Columns.Add("NameMessage", typeof(string));
所以这是起始DataTable（默认检索）：
Date Time Day Name Place DateTimeCombined NameMessage
6/29/2017 8:30AM MON John Orlance 6/29/2017 8:30:00 AM
6/29/2017 8:40AM MON John Orlance 6/29/2017 8:40:00 AM
6/29/2017 8:50AM MON John Orlance 6/29/2017 8:50:00 AM
6/29/2017 9:10AM MON John Orlance 6/29/2017 9:10:00 AM
6/29/2017 9:20AM MON John Orlance 6/29/2017 9:20:00 AM
6/29/2017 1:00PM MON John Orlance 6/29/2017 1:00:00 PM
6/30/2017 8:30AM TUE John Orlance 6/30/2017 8:30:00 AM
6/30/2017 8:40AM TUE John Orlance 6/30/2017 8:40:00 AM
6/29/2017 8:15AM MON Mike Atlanta 6/29/2017 8:15:00 AM
6/29/2017 8:30AM MON Mike Atlanta 6/29/2017 8:30:00 AM
6/29/2017 8:40AM MON Mike Atlanta 6/29/2017 8:40:00 AM
6/29/2017 9:10AM MON Mike Atlanta 6/29/2017 9:10:00 AM
6/29/2017 9:20AM MON Mike Atlanta 6/29/2017 9:20:00 AM
6/30/2017 8:30AM TUE Mike Atlanta 6/30/2017 8:30:00 AM
6/30/2017 8:40AM TUE Mike Atlanta 6/30/2017 8:40:00 AM
Christine Marion None
Steph Kearney None
6/29/2017 8:30AM MON Jenny Boise 6/29/2017 8:30:00 AM
6/29/2017 8:40AM MON Jenny Boise 6/29/2017 8:40:00 AM
6/29/2017 8:50AM MON Jenny Boise 6/29/2017 8:50:00 AM
6/29/2017 9:10AM MON Jenny Boise 6/29/2017 9:10:00 AM
6/29/2017 9:20AM MON Jenny Boise 6/29/2017 9:20:00 AM
6/30/2017 8:30AM TUE Jenny Boise 6/30/2017 8:30:00 AM
6/30/2017 8:40AM TUE Jenny Boise 6/30/2017 8:40:00 AM
6/29/2017 8:30AM MON Kelly Ardsley 6/29/2017 8:30:00 AM
6/29/2017 8:40AM MON Kelly Ardsley 6/29/2017 8:40:00 AM
6/29/2017 8:50AM MON Kelly Ardsley 6/29/2017 8:50:00 AM
6/29/2017 9:10AM MON Kelly Ardsley 6/29/2017 9:10:00 AM
6/29/2017 9:20AM MON Kelly Ardsley 6/29/2017 9:20:00 AM
6/30/2017 8:30AM TUE Kelly Ardsley 6/30/2017 8:30:00 AM
6/30/2017 8:40AM TUE Kelly Ardsley 6/30/2017 8:40:00 AM
Joseph Houston None
第一个LINQ函数应该是为每个Name获取更早的DateTimeCombined：
6/29/2017 8:30AM MON John Orlance 6/29/2017 8:30:00 AM
6/29/2017 8:15AM MON Mike Atlanta 6/29/2017 8:15:00 AM
6/29/2017 8:30AM MON Jenny Boise 6/29/2017 8:30:00 AM
6/29/2017 8:30AM MON Kelly Ardsley 6/29/2017 8:30:00 AM
下一个功能应该是按DateTimeCombined：
- If `DateTimeCombined` is same, order first by `DateTimeCombined` and then by Name.
- If `DateTimeCombined` is same AND Name is same, order first by `DateTimeCombined` and then by Name and then by Place.
6/29/2017 8:15AM MON Mike Atlanta 6/29/2017 8:15:00 AM
6/29/2017 8:30AM MON Jenny Boise 6/29/2017 8:30:00 AM
6/29/2017 8:30AM MON John Orlance 6/29/2017 8:30:00 AM
6/29/2017 8:30AM MON Kelly Ardsley 6/29/2017 8:30:00 AM
下一个函数应该是为每个名称添加其余行（最终的DataTable应该如下所示）：
6/29/2017 8:15AM MON Mike Atlanta 6/29/2017 8:15:00 AM
6/29/2017 8:30AM MON Mike Atlanta 6/29/2017 8:30:00 AM
6/29/2017 8:40AM MON Mike Atlanta 6/29/2017 8:40:00 AM
6/29/2017 9:10AM MON Mike Atlanta 6/29/2017 9:10:00 AM
6/29/2017 9:20AM MON Mike Atlanta 6/29/2017 9:20:00 AM
6/30/2017 8:30AM TUE Mike Atlanta 6/30/2017 8:30:00 AM
6/30/2017 8:40AM TUE Mike Atlanta 6/30/2017 8:40:00 AM
6/29/2017 8:30AM MON Jenny Boise 6/29/2017 8:30:00 AM
6/29/2017 8:40AM MON Jenny Boise 6/29/2017 8:40:00 AM
6/29/2017 8:50AM MON Jenny Boise 6/29/2017 8:50:00 AM
6/29/2017 9:10AM MON Jenny Boise 6/29/2017 9:10:00 AM
6/29/2017 9:20AM MON Jenny Boise 6/29/2017 9:20:00 AM
6/30/2017 8:30AM TUE Jenny Boise 6/30/2017 8:30:00 AM
6/30/2017 8:40AM TUE Jenny Boise 6/30/2017 8:40:00 AM
6/29/2017 8:30AM MON John Orlance 6/29/2017 8:30:00 AM
6/29/2017 8:40AM MON John Orlance 6/29/2017 8:40:00 AM
6/29/2017 8:50AM MON John Orlance 6/29/2017 8:50:00 AM
6/29/2017 9:10AM MON John Orlance 6/29/2017 9:10:00 AM
6/29/2017 9:20AM MON John Orlance 6/29/2017 9:20:00 AM
6/29/2017 1:00PM MON John Orlance 6/29/2017 1:00:00 PM
6/30/2017 8:30AM TUE John Orlance 6/30/2017 8:30:00 AM
6/30/2017 8:40AM TUE John Orlance 6/30/2017 8:40:00 AM
6/29/2017 8:30AM MON Kelly Ardsley 6/29/2017 8:30:00 AM
6/29/2017 8:40AM MON Kelly Ardsley 6/29/2017 8:40:00 AM
6/29/2017 8:50AM MON Kelly Ardsley 6/29/2017 8:50:00 AM
6/29/2017 9:10AM MON Kelly Ardsley 6/29/2017 9:10:00 AM
6/29/2017 9:20AM MON Kelly Ardsley 6/29/2017 9:20:00 AM
6/30/2017 8:30AM TUE Kelly Ardsley 6/30/2017 8:30:00 AM
6/30/2017 8:40AM TUE Kelly Ardsley 6/30/2017 8:40:00 AM
注意：例如，如果凯利是约翰（约翰出现两次），那么Ardsley小组将会在Orlance之前进行。
到目前为止我尝试了什么：
var ordered = dataTable.AsEnumerable().OrderBy(en => en.Field<DateTime>("DateTimeCombined")).CopyToDataTable();
更新
var ordered = dataTable.AsEnumerable()
.OrderBy(en => en.Field<DateTime>("DateTimeCombined"))
.GroupBy(en1 => en1.Field<string>("Name")).ToList();
只给我这个名字。
更新
var q = dataTable.AsEnumerable()
.GroupBy(item => item.Field<string>("Name"))
.SelectMany(grouping => grouping.Take(1))
.OrderBy(item => item.Field<DateTime>("CombinedDateTime"))
.ThenBy(item => item.Field<string>("Name"))
.ThenBy(item => item.Field<string>("Place"))
.CopyToDataTable();
以上工作符合预期：
6/29/2017 8:15AM MON Mike Atlanta 6/29/2017 8:15:00 AM
6/29/2017 8:30AM MON Jenny Boise 6/29/2017 8:30:00 AM
6/29/2017 8:30AM MON John Orlance 6/29/2017 8:30:00 AM
6/29/2017 8:30AM MON Kelly Ardsley 6/29/2017 8:30:00 AM
但仅当我取每组的第一行（按名称）时。如果我按组进行所有操作，则所有行都会混淆。我现在怎么样，在Mike的行之后追加剩余的Mike's行，在Jenny的行之后追加剩余的Jenny's行，依此类推？这可以在同一个LINQ中完成吗？
答案 0 :(得分：3)
根据新编辑的问题，我有：
var ordered = dataT.AsEnumerable()
.GroupBy(en => new { Name = en.Field<string>("Name"), Place = en.Field<string>("Place") })
.OrderBy(eng => eng.Min(en => en.Field<DateTime>("DateTimeCombined")))
.ThenBy(eng => eng.Key.Name).ThenBy(eng => eng.Key.Place)
.SelectMany(eng => eng.OrderBy(en => en.Field<DateTime>("DateTimeCombined")), (eng, en) => en)
.CopyToDataTable();