Compare, Find and Display Uncommon (Not Matching) rows between two GridView in ASP.Net

Here I have created sample that Compares GridView1 to GridView2 and vice-versa.you can compare only GridView1 to GridView2 by just doing some modification in given code.

HTML

<div>
    First Grid:
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false">
        <Columns>
            <asp:BoundField DataField="Id" HeaderText="Id" ItemStyle-Width="30" />
            <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="150" />
            <asp:BoundField DataField="Country" HeaderText="Country" ItemStyle-Width="150" />
        </Columns>
    </asp:GridView>
    <br />
    Second Grid:
    <asp:GridView ID="GridView2" runat="server" AutoGenerateColumns="false">
        <Columns>
            <asp:BoundField DataField="Id" HeaderText="Id" ItemStyle-Width="30" />
            <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="150" />
            <asp:BoundField DataField="Country" HeaderText="Country" ItemStyle-Width="150" />
        </Columns>
    </asp:GridView>
    <br />
    <br />
    <asp:Button Text="Get Uncommon Data" runat="server" OnClick="GetUncommonData" />
    <asp:GridView ID="GridView3" runat="server" AutoGenerateColumns="false">
        <Columns>
            <asp:BoundField DataField="Id" HeaderText="Id" ItemStyle-Width="30" />
            <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="150" />
            <asp:BoundField DataField="Country" HeaderText="Country" ItemStyle-Width="150" />
        </Columns>
    </asp:GridView>
</div>

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        BindGrid1();
        BindGrid2();
    }
}

private void BindGrid1()
{
    DataTable dt = new DataTable();
    dt.Columns.AddRange(new DataColumn[3] { new DataColumn("Id", typeof(int)),
                        new DataColumn("Name", typeof(string)),
                        new DataColumn("Country",typeof(string)) });
    dt.Rows.Add(1, "John Hammond", "United States");
    dt.Rows.Add(2, "Mudassar Khan", "India");
    dt.Rows.Add(3, "Suzanne Mathews", "France");
    dt.Rows.Add(4, "Robert Schidner", "Russia");
    GridView1.DataSource = dt;
    ViewState["Grid1Data"] = dt;
    GridView1.DataBind();
}

private void BindGrid2()
{

    DataTable dt = new DataTable();
    dt.Columns.AddRange(new DataColumn[3] { new DataColumn("Id", typeof(int)),
                        new DataColumn("Name", typeof(string)),
                        new DataColumn("Country",typeof(string)) });
    dt.Rows.Add(1, "John Hammond", "United States");
    dt.Rows.Add(2, "Mudassar Khan", "India");
    dt.Rows.Add(6, "David", "France");
    dt.Rows.Add(8, "Kevin", "Russia");
    GridView2.DataSource = dt;
    ViewState["Grid2Data"] = dt;
    GridView2.DataBind();
}

protected void GetUncommonData(object sender, EventArgs e)
{
    DataTable dt1 = (DataTable)ViewState["Grid1Data"];
    DataTable dt2 = (DataTable)ViewState["Grid2Data"];
    var qry1 = dt1.AsEnumerable().Select(a => new { Id = a["Id"].ToString() });
    var qry2 = dt2.AsEnumerable().Select(b => new { Id = b["Id"].ToString() });

    var exceptAB = qry1.Except(qry2);

    var exceptBA = qry2.Except(qry1);

    var mismatchDataAB = (from a in dt1.AsEnumerable()
                            join ab in exceptAB on a["Id"].ToString() equals ab.Id
                            select a);

    var mismatchDataBA = (from a in dt2.AsEnumerable()
                            join ab in exceptBA on a["Id"].ToString() equals ab.Id
                            select a);
    var unCommon = mismatchDataAB.Union(mismatchDataBA);
    if (unCommon.ToArray().Length > 0)
    {
        GridView3.DataSource = unCommon.CopyToDataTable();
        GridView3.DataBind();
    }
}

Screenshot

you can also refer below link if you want to Compare whole row (ie. Id,Name,Country)

http://canlu.blogspot.in/2009/05/how-to-compare-two-datatables-in-adonet.html