c# - How to create a DataTable with distinct rows from a DataView

Create a new DataTable from a DataView with distinct values
DataTableFromADataViewWithDistinctValues.aspx

<%@ Page Language="C#" AutoEventWireup="true" %>
<%@ Import Namespace="System.Data" %>

<!DOCTYPE html>
<script runat="server">
    protected void Button1_Click(object sender, System.EventArgs e)
    {
        DataTable dt = new DataTable();
        dt.TableName = "Books";

        DataColumn dc1 = new DataColumn();
        dc1.ColumnName = "BookID";
        dc1.DataType = typeof(int);
        dc1.AllowDBNull = false;
        dc1.Unique = true;

        DataColumn dc2 = new DataColumn();
        dc2.ColumnName = "Category";
        dc2.DataType = typeof(string);

        DataColumn dc3 = new DataColumn();
        dc3.ColumnName = "BookName";
        dc3.DataType = typeof(string);

        DataColumn dc4 = new DataColumn();
        dc4.ColumnName = "Author";
        dc4.DataType = typeof(string);

        dt.Columns.AddRange(new DataColumn[] { dc1, dc2, dc3, dc4 });

        dt.Rows.Add(new object[] { 1, "Flash", "Papervision3D Essentials", "Jeff Winder, Paul Tondeur" });
        dt.Rows.Add(new object[] { 2, "JBoss", "jBPM Developer Guide", "Mauricio Salatino" });
        dt.Rows.Add(new object[] { 3, "Flash", "Flash Multiplayer Virtual Worlds", "Makzan" });
        dt.Rows.Add(new object[] { 4, "Flash", "Papervision3D Essentials", "Jeff Winder, Paul Tondeur" });
        dt.AcceptChanges();

        Label1.Text = "Source DataTable: " + dt.TableName;
        GridView1.DataSource = dt.DefaultView;
        GridView1.DataBind();

        //this line create a new DataView
        DataView dView = new DataView(dt);
        dView.RowFilter = "Category = 'Flash'";

        Label2.Text = "Here we create a new DataView<br />" +
                      "and set the RowFilter (Category = 'Flash')";

        GridView2.DataSource = dView;
        GridView2.DataBind();

        //this line create a new DataTable from DataView
        DataTable dt2 = dView.ToTable(false, "BookName", "Author");

        Label3.Text = "Here we create a new DataTable from DataView";

        GridView3.DataSource = dt2;
        GridView3.DataBind();

        //this line create a new DataTable from DataView with distinct values
        DataTable dt3 = dView.ToTable(true, "BookName", "Author");

        Label4.Text = "Here we create a new DataTable from DataView with distinct values";

        GridView4.DataSource = dt3;
        GridView4.DataBind();
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>How to create a new DataTable from a DataView with distinct values (rows) in ado.net</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h2 style="color:DarkBlue; font-style:italic;">
            How to create a new DataTable from a
            <br /> DataView with distinct values (rows) in ado.net
        </h2>
        <hr width="450" align="left" color="CornFlowerBlue" />
        <asp:Label
             ID="Label1"
             runat="server"
             Font-Size="Large"
             ForeColor="DodgerBlue"
             Font-Italic="true"
             >
        </asp:Label>
        <asp:GridView 
            ID="GridView1"
            runat="server"
            BorderColor="Snow"
            ForeColor="Snow"
            Width="750"
            Font-Names="Courier"
            >
            <HeaderStyle BackColor="HotPink" Height="30" />
            <RowStyle BackColor="OliveDrab" />
            <AlternatingRowStyle BackColor="DarkOliveGreen" />
        </asp:GridView>
        <asp:Label
             ID="Label2"
             runat="server"
             Font-Size="Large"
             ForeColor="DodgerBlue"
             Font-Italic="true"
             >
        </asp:Label>
        <asp:GridView 
            ID="GridView2"
            runat="server"
            BorderColor="Snow"
            ForeColor="Snow"
            Width="750"
            Font-Names="Courier"
            >
            <HeaderStyle BackColor="HotPink" Height="30" />
            <RowStyle BackColor="OliveDrab" />
            <AlternatingRowStyle BackColor="DarkOliveGreen" />
        </asp:GridView>
        <asp:Label
             ID="Label3"
             runat="server"
             Font-Size="Large"
             ForeColor="DodgerBlue"
             Font-Italic="true"
             >
        </asp:Label>
        <asp:GridView 
            ID="GridView3"
            runat="server"
            BorderColor="Snow"
            ForeColor="Snow"
            Width="750"
            Font-Names="Courier"
            >
            <HeaderStyle BackColor="HotPink" Height="30" />
            <RowStyle BackColor="OliveDrab" />
            <AlternatingRowStyle BackColor="DarkOliveGreen" />
        </asp:GridView>
        <asp:Label
             ID="Label4"
             runat="server"
             Font-Size="Large"
             ForeColor="DodgerBlue"
             Font-Italic="true"
             >
        </asp:Label>
        <asp:GridView 
            ID="GridView4"
            runat="server"
            BorderColor="Snow"
            ForeColor="Snow"
            Width="750"
            Font-Names="Courier"
            >
            <HeaderStyle BackColor="HotPink" Height="30" />
            <RowStyle BackColor="OliveDrab" />
            <AlternatingRowStyle BackColor="DarkOliveGreen" />
        </asp:GridView>
        <asp:Button 
            ID="Button1"
            runat="server"
            OnClick="Button1_Click"
            Text="Populate GridView"
            Height="45"
            Font-Bold="true"
            ForeColor="DodgerBlue"
            />
    </div>
    </form>
</body>
</html>
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