Sorting GridView

First of all drag the GridView control from Data controls menu. It will add the GridView control HTML source code as given above. Now click on GridView control to load the control properties at right side panel.

<asp:GridView id="GridView1" runat="server"></asp:GridView>

To allow the sorting in GridView control select True from the dropdown list of AllowSorting property of Gridview as shown in above image.
This will add AllowSorting="True" in HTML source code of GridView Control.
Next step is to bind the Sorting event for GridView Control.

To bind the Sorting event of GridView control, double click on the Sorting event in the properties viewer of GridView. This will add the Sorting event in the HTML source code and C# code for Gridview.

HTML Source code for GridView Sorting

<asp:GridView ID="GridView1"
              runat="server"
              CellPadding="2"
              AllowSorting="True"
              OnSorting="GridView1_Sorting"
              AutoGenerateColumns="False"
              Width="500px">
    <Columns>

        <asp:BoundField DataField="ProductID" HeaderText="ProductID" SortExpression="ProductName">
            <HeaderStyle HorizontalAlign="Left" />
        </asp:BoundField>

        <asp:BoundField DataField="ProductName" HeaderText="Product Name" SortExpression="ProductName">
            <HeaderStyle HorizontalAlign="Left" Width="200px" />
        </asp:BoundField>

        <asp:BoundField DataField="UnitsInStock" HeaderText="Units In Stock" SortExpression="UnitsInStock">
            <HeaderStyle HorizontalAlign="Left" />
            <ItemStyle HorizontalAlign="Center" />
        </asp:BoundField>

        <asp:BoundField DataField="UnitPrice" HeaderText="Price Per Unit" SortExpression="UnitPrice">
            <HeaderStyle HorizontalAlign="Left" />
            <ItemStyle HorizontalAlign="Center" />
        </asp:BoundField>

    </Columns>
</asp:GridView>

C# Code for GridView Sorting

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ViewState["sortOrder"] = "";
            bindGridView("","");
        }
    }

    public void bindGridView(string sortExp,string sortDir)
    {
        // string variable to store the connection string
        // defined in ConnectionStrings section of web.config file.
        string connStr = ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString;

        // object created for SqlConnection Class.
        SqlConnection mySQLconnection = new SqlConnection(connStr);

        // if condition that can be used to check the sql connection
        // whether it is already open or not.
        if (mySQLconnection.State == ConnectionState.Closed)
        {
            mySQLconnection.Open();
        }

        SqlCommand mySqlCommand = new SqlCommand("select top 10 ProductID, ProductName, UnitsInStock, UnitPrice from products", mySQLconnection);
        SqlDataAdapter mySqlAdapter = new SqlDataAdapter(mySqlCommand);
        DataSet myDataSet = new DataSet();
        mySqlAdapter.Fill(myDataSet);

        DataView myDataView = new DataView();
        myDataView = myDataSet.Tables[0].DefaultView;

        if (sortExp!=string.Empty)
        {
            myDataView.Sort = string.Format("{0} {1}", sortExp, sortDir);
        }

        GridView1.DataSource = myDataView;
        GridView1.DataBind();

        // if condition that can be used to check the sql connection
        // if it is open then close it.
        if (mySQLconnection.State == ConnectionState.Open)
        {
            mySQLconnection.Close();
        }

    }

    protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
    {
     
        bindGridView(e.SortExpression, sortOrder);
       
    }

    public string sortOrder
    {
        get
        {
            if (ViewState["sortOrder"].ToString() == "desc")
            {
                ViewState["sortOrder"] = "asc";
            }
            else
            {
                ViewState["sortOrder"] = "desc";
            }

            return ViewState["sortOrder"].ToString();
        }
        set
        {
            ViewState["sortOrder"] = value;
        }
    }

Output:

Get the output for above discussed code from the following link: