fetch data on selected index of dropdownlist

Here I have created sample.

HTML

<div>
    Select Table:
    <asp:DropDownList ID="ddlTables" runat="server" OnSelectedIndexChanged="TableChanged"
        AutoPostBack="true">
        <asp:ListItem Text="Fruit" Value="Fruit" />
        <asp:ListItem Text="Hobbies" Value="Hobbies" />
    </asp:DropDownList>
    <br />
    <br />
    <asp:GridView ID="gvData" runat="server" />
</div>

C#

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

protected void TableChanged(object sender, EventArgs e)
{
    BindGrid();
}

private void BindGrid()
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    string query = "SELECT * FROM " + ddlTables.SelectedItem.Value + ";";


    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand(query))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                sda.SelectCommand = cmd;
                using (DataTable dt = new DataTable())
                {
                    sda.Fill(dt);
                    gvData.DataSource = dt;
                    gvData.DataBind();
                }
            }
        }
    }
}

Screenshot