c# - copie uniquement les données sélectionnées à nouveau datatable avec linq - Stack Overflow

I've searched the web for quite some time now and can't seem to find an elegant way to

• read data from one datatable,


• group it by two variables with linq


• select only those two variables (forget about the others in the source datatable) and


• copy these items to a new datatable.

I got it working without selecting specific variables, but at the amount of data the program is going to process later I'd rather only copy what's really needed.

var temp123 = from row in oldDataTable.AsEnumerable()
              orderby row["Column1"] ascending
              group row by new { Column1 = row["Column1"], Column2 = row["Column2"] } into grp
              select grp.First();

newDataTable = temp123.CopyToDataTable();

Can anyone please be so kind to help me out here? Thanks!

You can use custom implementation of CopyToDataTable method from this article How to: Implement CopyToDataTable Where the Generic Type T Is Not a DataRow

newDataTable = 
    oldDataTable
       .AsEnumerable()
       .GroupBy(r => new { Column1 = row["Column1"], Column2 = row["Column2"] })
       .Select(g => g.First())
       .OrderBy(x => x.Column1)
       .CopyToDataTable(); // your custom extension

Another option, as Tim suggested - manual creation of DataTable.

var newDataTable = new DataTable();
newDataTable.Columns.Add("Column1");
newDataTable.Columns.Add("Column2");

foreach(var item in temp123)
    newDataTable.Rows.Add(item.Column1, item.Column2);

And last option (if possible) - don't use DataTable - simply use collection of strongly typed objects.

I've searched the web for quite some time now and can't seem to find an elegant way to

• read data from one datatable,


• group it by two variables with linq


• select only those two variables (forget about the others in the source datatable) and


• copy these items to a new datatable.

I got it working without selecting specific variables, but at the amount of data the program is going to process later I'd rather only copy what's really needed.

var temp123 = from row in oldDataTable.AsEnumerable()
              orderby row["Column1"] ascending
              group row by new { Column1 = row["Column1"], Column2 = row["Column2"] } into grp
              select grp.First();

newDataTable = temp123.CopyToDataTable();

Can anyone please be so kind to help me out here? Thanks!

You can use custom implementation of CopyToDataTable method from this article How to: Implement CopyToDataTable Where the Generic Type T Is Not a DataRow

newDataTable = 
    oldDataTable
       .AsEnumerable()
       .GroupBy(r => new { Column1 = row["Column1"], Column2 = row["Column2"] })
       .Select(g => g.First())
       .OrderBy(x => x.Column1)
       .CopyToDataTable(); // your custom extension

Another option, as Tim suggested - manual creation of DataTable.

var newDataTable = new DataTable();
newDataTable.Columns.Add("Column1");
newDataTable.Columns.Add("Column2");

foreach(var item in temp123)
    newDataTable.Rows.Add(item.Column1, item.Column2);

And last option (if possible) - don't use DataTable - simply use collection of strongly typed objects.

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