public partial class index : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        ShowAllInfo(GetAllInfo());
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        ShowAllInfo(GetAllInfo());
    }
    public object GetAllInfo()
    {
        return QuestionBll.GetAllInfo(txtNum_case.Text.ToString(), txtNam_cust.Text.ToString(),ddl.SelectedValue.ToString(), s2.Value.ToString());
    }
    public void ShowAllInfo(object entities)
    {
        this.GridView1.DataSource = entities;
        this.GridView1.DataBind();
    }
}

//show index
        public static DataSet GetAllInfo(string num_case, string nam_cust, string sts_custcar,string dat_car)
        {
            string sql = "select a.typ_custcar,a.num_case,a.nam_cust,a.dat_car,a.car_note,a.solution,b.content AS nam_dept_fix,a.dat_plnfix ,a.dat_actfix,a.sts_custcar from web_caseproj_custcars a ";
            sql = sql + string.Format("left join web_codd b on a.dept_fix = b.code and b.code_id = 'FIXDEPT' where 1=1 ");
            if (num_case != "")
            {
                sql = sql + string.Format("and num_case = '{0}' ", num_case);
            }
            else if (nam_cust != "")
            {
                sql = sql + string.Format("and nam_cust = '{0}' ", nam_cust);
            }
            else if (sts_custcar != "")
            {
                sql = sql + string.Format("and sts_custcar = '{0}' ", sts_custcar);
            }
            else if (dat_car != "")
            {
                sql = sql + string.Format("and dat_car = '{0}' ", DateTime.Parse(dat_car).ToString("yyyyMMdd"));
            }
            else
            {
                sql = sql + string.Format(" order by dat_car");
            }
            DataSet ds = DBhelpe.ExcuteDataSet(sql);
            return ds;
        }