void Application_BeginRequest(object sender, EventArgs e)
{
    bool result = false;
    if (Request.RequestType.ToUpper() == "POST")
    {
       //post方式的我就不写了。
    }
    else
    {
      result = ValidUrlGetData();
    }
    if (result)
    {
      Response.Write("您提交的数据有恶意字符！");
      Response.End();
    }
}
/// <summary>
/// 获取QueryString中的数据
/// </summary>
public static bool ValidUrlGetData()
{
    bool result = false;
    for (int i = 0; i < HttpContext.Current.Request.QueryString.Count; i++)
    {
      result = Validate(HttpContext.Current.Request.QueryString[i].ToString());
      if (result)
      {
        break;
      }//如果检测存在漏洞
    }
    return result;
}
public static string []strs = new string[] {"select","drop","exists","exec","insert","delete","update","and","or","user" };//此处我随便加了几个，大家可以多加点哈。
public static bool Validate(string str)
{
    for (int i = 0; i < strs.Length; i++)
    {
      if (str.IndexOf(strs[i]) != -1)
      {
        return true;
        break;
      }
    }
    return false;
}