How do I use SELECT GROUP BY in DataTable.Select(Expression)?

Question

I try to remove the duplicate rows by select a first row from every group. For Example

PK     Col1     Col2
1        A        B
2        A        B
3                 


        

Answer 1

dt.AsEnumerable()
    .GroupBy(r => new { Col1 = r["Col1"], Col2 = r["Col2"] })
    .Select(g =>
    {
        var row = dt.NewRow();

        row["PK"] = g.Min(r => r.Field("PK"));
        row["Col1"] = g.Key.Col1;
        row["Col2"] = g.Key.Col2;

        return row;

    })
    .CopyToDataTable();