DataRelation: How to compare specific columns

Question

I am comparing two datatables using the answer in this link Compare two Datatables but when I use the DataRelation function I am getting an error that both columns length should match. but I want to only compare specific columns.

Currently I have it this way:

// Using a Dataset to make use of a DataRelation Object
using (DataSet ds = new DataSet())
{
    //Add Tables
    ds.Tables.AddRange(new DataTable[] { dt.Copy(), dataTable.Copy() });

    //Get  First Columns for DataRelation
    DataColumn[] firstcolumns = new DataColumn[7];
    firstcolumns[0] = ds.Tables[0].Columns[0];
    firstcolumns[1] = ds.Tables[0].Columns[1];
    firstcolumns[2] = ds.Tables[0].Columns[2];
    firstcolumns[3] = ds.Tables[0].Columns[3];
    firstcolumns[4] = ds.Tables[0].Columns[4];
    firstcolumns[5] = ds.Tables[0].Columns[5];
    firstcolumns[6] = ds.Tables[0].Columns[6];

    //Get Second Columns for DataRelation
    DataColumn[] secondcolumns = new DataColumn[8];
    secondcolumns[0] = ds.Tables[1].Columns[0];
    secondcolumns[1] = ds.Tables[1].Columns[1];
    secondcolumns[2] = ds.Tables[1].Columns[2];
    secondcolumns[3] = ds.Tables[1].Columns[3];
    secondcolumns[4] = ds.Tables[1].Columns[4];
    secondcolumns[5] = ds.Tables[1].Columns[5];
    secondcolumns[6] = ds.Tables[1].Columns[6];
    secondcolumns[7] = ds.Tables[1].Columns[7];

    //Create DataRelation
    DataRelation r = new DataRelation(string.Empty, firstcolumns, secondcolumns, false);

    ds.Relations.Add(r);

    //Create Columns for return table
    for(int i = 0; i < dt.Columns.Count ; i++ )
    {
        ResultDataTable.Columns.Add(dt.Columns[i].ColumnName, dt.Columns[i].DataType);
    }

    //If first Row not in second, add to return table
    ResultDataTable.BeginLoadData();

    foreach( DataRow parentrow in ds.Tables[0].Rows)
    {
        DataRow[] childrows = parentrow.GetChildRows(r);
        if (childrows != null || childrows.Length != 0)
        {
            ResultDataTable.LoadDataRow(parentrow.ItemArray, true);
        }
    }

    ResultDataTable.EndLoadData();

    ResultDataTable.AsDataView();

    //Export to Excel
    ResultDataTable.WriteXml("data.xls");
}

What I want to do is if all the columns in firstcolumns match columns 1, 2, 3, 4, 5, 6, 7 in second columns load the all the second columns (including 0) into the resultdatatable

Please can you advice how I can do this?

Answer 1

I solved this using LINQ. Got a bit of help on Stackoverflow. Following is the link to my question: Compare datatables using LINQ