<pre lang="c#">
 protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            BindData();
        }
    }
 private void BindData()
    {
        if (ddlTguidedit.SelectedIndex==0)
        {
            string strQuery = "SELECT [Pdfid],[Arpdf_name],[Arpdf_des],[pdf_date] FROM [books_alaa].[dbo].[Tbl_uploadpdf]";
            SqlCommand cmd = new SqlCommand(strQuery);
            GridView1.DataSource = GetData(cmd);
            GridView1.DataBind();
        }
        else
        {
            string strQuery = " SELECT Pdfid, Enpdf_name AS Arpdf_name, Enpdf_des AS Arpdf_des, pdf_url, pdf_date FROM Tbl_uploadpdf";
            SqlCommand cmd = new SqlCommand(strQuery);
            GridView1.DataSource = GetData(cmd);
            GridView1.DataBind();
        }
    }
    private DataTable GetData(SqlCommand cmd)
    {
        DataTable dt = new DataTable();
        SqlConnection con = new SqlConnection(strConnString);
        SqlDataAdapter sda = new SqlDataAdapter();
        cmd.CommandType = CommandType.Text;
        cmd.Connection = con;
        con.Open();
        sda.SelectCommand = cmd;
        sda.Fill(dt);
        return dt;
    }
 protected void ddlTguidedit_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (ddlTguidedit.SelectedIndex == 0)
        {
            string strQuery = "SELECT [Pdfid],[Arpdf_name],[Arpdf_des],[pdf_date] FROM [books_alaa].[dbo].[Tbl_uploadpdf]";
            SqlCommand cmd = new SqlCommand(strQuery);
            GridView1.DataSource = GetData(cmd);
            GridView1.DataBind();
        }
        else
        {
            string strQuery = " SELECT Pdfid, Enpdf_name AS Arpdf_name, Enpdf_des AS Arpdf_des, pdf_url, pdf_date FROM Tbl_uploadpdf";
            SqlCommand cmd = new SqlCommand(strQuery);
            GridView1.DataSource = GetData(cmd);
            GridView1.DataBind();
        }
    }
</pre>
why it doesnt work ??