Question

我有DataTable值：

ID  NameID  Name
1   1       qwe
2   2       ert  
3   2       ert  
4   3       dffg 
5   3       dffg

我希望得到一个包含不同行的DataTable：

ID  NameID  Name
1   1       qwe
2   2       ert
4   3       dffg

如何使用LINQ或其他方法实现这一目标？

Answer 1

var rows = tbl.AsEnumerable().Select(row => row).ToList();
tbl = new DataTable();
tbl.Columns.Add("ID", typeof(Int32));
tbl.Columns.Add("NameID", typeof(Int32));
tbl.Columns.Add("Name", typeof(String));

rows.GroupBy(r => r.Field<int>("NameID"))                
    .Select(rr => rows.First(rw => rw.Field<Int32>("NameID") == rr.Key))
    .ToList()
    .ForEach(rname => tbl.Rows.Add(new object []
        {                                                 
            rname.Field<Int32>("ID"),
            rname.Field<Int32>("NameID"),
            rname.Field<String>("Name"),                    
        }));

测试数据设置：

DataTable tbl = new DataTable();
tbl.Columns.Add("ID", typeof (Int32));
tbl.Columns.Add("NameID", typeof (Int32));
tbl.Columns.Add("Name", typeof (String));

tbl.Rows.Add(new object[] { 1, 1, "qwe" });
tbl.Rows.Add(new object[] { 2, 2, "ert" });
tbl.Rows.Add(new object[] { 3, 2, "ert" });
tbl.Rows.Add(new object[] { 4, 3, "dffg" });
tbl.Rows.Add(new object[] { 5, 3, "dffg" });

Answer 2

将数据表分配给数据视图，使用dataview对象，我们可以使用RowFilter，如下所示。

                Dim DTb As New DataTable()
                DataView dView= new DataView(DTb); 
                dView.RowFilter = strCondition.ToString //strCondition contains the condition to filter

strCondition将包含要过滤的条件，并在过滤后将数据视图重新分配给数据表，如下所示

                DTb = dView.ToTable()

Answer 3

尝试，

 var result = from ele in dt.AsEnumerable()
               group ele by ele["NameID"] into g
               select g.FirstOrDefault();

  foreach (var t in result)
     Console.WriteLine(t[0] + " " + t[1] + " " + t[2]);

从数据表中获取不同的值

3 个答案: