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c# - How to create a DataTable from a DataView

DataView ToTable() method
.Net framework's DataView represents a data bindable, customized view of a DataTable for filtering, sorting, searching, editing, and navigation. DataView does not store any data, it represents a connected view of its corresponding DataTable. DataTable represents one table of in-memory data.

DataView ToTable() method has four overloaded methods, those are ToTable(), ToTable(String), ToTable(Boolean, String[]), and ToTable(String, Boolean, String[]).

DataView ToTable() method creates and returns a new DataTable based on rows in an existing DataView. This method return value type is System.Data.DataTable which represents a new DataTable instance that contains the requested rows and columns. This method returned DataTable contains the same columns as the input table. Returned DataTable name is also the same as the source DataTable.

DataView ToTable(String) overloaded method also creates and returns a DataTable based on rows in an existing DataView. The ToTable(String) method requires passing a parameter named tableName. This parameter value represents the name of the returned DataTable. This method's returned DataTable contains the same columns as the input table. But we can specify a table name of the returned DataTable.

DataView ToTable(Boolean, String[]) overloaded method has two required parameters named distinct and columnNames. The distinct parameter value data type is a Boolean. This parameter value true indicates the returned DataTable contains rows that have distinct values for all its columns. This parameter's default value is false.

ToTable(Boolean, String[]) method's 'columnNames' parameter value type is System.String[] which represents a string array that contains a list of column names to be included in the returned DataTable object. So by using this parameter we can specify whether returned DataTable contains only distinct rows and we also can specify the column names.

DataView ToTable(String, Boolean, String[]) overloaded method requires passing three parameters named tableName, distinct, and columnNames. Using this method we can specify returned DataTable's table name, and column names and whether it contains only distinct values for all its columns or not.

The following ADO.NET C# example code demonstrates to us how can we create a new DataTable based on rows in an existing DataView programmatically at run time in an ASP.NET application.
DataViewToTableMethod.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, "iPhone", "iPhone User Interface Cookbook: RAW", "Cameron Banga" });
        dt.Rows.Add(new object[] { 2, "MySQL", "MySQL 5.1 Plugin Development", "Andrew Hutchings, Sergei Golubchik" });
        dt.Rows.Add(new object[] { 3, "MySQL", "MySQL Admin Cookbook", "Daniel Schneller, Udo Schwedt" });
        dt.AcceptChanges();

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

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

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

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

        //this line create a new DataTable from DataView
        DataTable dt2 = dView.ToTable();

        Label3.Text = "Here we create a new DataTable from DataView";
        GridView3.DataSource = dt2;
        GridView3.DataBind();
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>How to use DataView ToTable method to create a new DataTable in ado.net</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h2 style="color:DarkBlue; font-style:italic;">
            How to use DataView ToTable method
            <br /> to create a new DataTable 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="600"
            Font-Names="Courier"
            >
            <HeaderStyle BackColor="DarkSlateBlue" Height="30" />
            <RowStyle BackColor="MediumVioletRed" />
            <AlternatingRowStyle BackColor="PaleVioletRed" />
        </asp:GridView>
        <br />
        <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="600"
            Font-Names="Courier"
            >

            <HeaderStyle BackColor="DarkSlateBlue" Height="30" />
            <RowStyle BackColor="MediumVioletRed" />
            <AlternatingRowStyle BackColor="PaleVioletRed" />
        </asp:GridView>
        <br />
        <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="600"
            Font-Names="Courier"
            >
            <HeaderStyle BackColor="DarkSlateBlue" Height="30" />
            <RowStyle BackColor="MediumVioletRed" />
            <AlternatingRowStyle BackColor="PaleVioletRed" />
        </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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