Filtravimas su Linq

Sveiki,

Reiktu patarimo kaip geriau viena varianta issukti (galva nebenesa).

Turiu viena lenta, kuri turi sarysius su nemazai kitu lentu. Duomenys isvedami i GridView (na tas ne tiek svarbu). Reikia padaryti filtravima pagal viena ar kelis is tu lauku.

 protected void filterBtn_Click(object sender, EventArgs e)
    {
        DataBaseDataContext db = new DataBaseDataContext();

        IEnumerable<RiskRegister> q = from p in db.RiskRegisters select p;


       
        //DataControlFieldCollection col = GridView1.Columns;
        
        if (SortNumericddl.SelectedIndex != 0)
        {
            if (q.Count() != 0)
            //q = from p in q where p.Id == int.Parse(SortNumericddl.SelectedValue) select p;
            q= q.Where(p => p.Id == int.Parse(SortNumericddl.SelectedValue));
        }
        if (SortDamageType.SelectedIndex != 0)
        {
            if (q.Count()!=0)
            q = from p in q where p.DamageTypeId == int.Parse(SortDamageType.SelectedValue) select p;
        }
        if (SortRiskReason.SelectedIndex != 0)
        {
            if (q.Count() != 0)
            q = from p in q where p.RiskReasonTypeId == int.Parse(SortRiskReason.SelectedValue) select p;
        }
        if (SortRiskControlStatus.SelectedIndex != 0)
        {
            if (q.Count() != 0)
            q = from p in q where p.RiskControlStatusId == int.Parse(SortRiskControlStatus.SelectedValue) select p;
        }
        if (SortRiskResponseStatus.SelectedIndex != 0)
        {
            if (q.Count() != 0)
               
                q = from p in q where p.RiskResponseStatusId == int.Parse(SortRiskResponseStatus.SelectedValue) select p;
        }
        if (SortRiskTutor.SelectedIndex != 0)
        {
            if (q.Count() != 0)
                q = from p in q where p.RiskTutor == int.Parse(SortRiskTutor.SelectedValue) select p;
        }
        if (SortRiskMasterName.SelectedIndex != 0)
        {
            if (q.Count() != 0)
                q = from p in q where p.RiskCompanyId == int.Parse(SortRiskMasterName.SelectedValue) select p;
        }
        if (SortRiskMasterName.SelectedIndex != 0)
        {
            if (q.Count() != 0)
                q = from p in q where p.RiskCompanyId == int.Parse(SortRiskMasterName.SelectedValue) select p;
        }
        if (SortRiskChance.SelectedIndex != 0)
        {
            if (q.Count() != 0)
                q = from p in q where p.RiskChanceId == int.Parse(SortRiskChance.SelectedValue) select p;
        }
        if (SortRiskResultName.SelectedIndex != 0)
        {
            if (q.Count() != 0)
                q = from p in q where p.RiskResultId == int.Parse(SortRiskResultName.SelectedValue) select p;
        }
        if (SortRiskTotalName.SelectedIndex != 0)
        {
            if (q.Count() != 0)
                q = from p in q where p.RiskTotalTypeId == int.Parse(SortRiskTotalName.SelectedValue) select p;
        }
        if (SortRiskServiceName.SelectedIndex != 0)
        {
            if (q.Count() != 0)
                q = from p in q where p.RiskServiceId == int.Parse(SortRiskServiceName.SelectedValue) select p;
        }
        
        if (q.Count() > 0)
        {
            int mm = q.Count();
            /*var t = from m in q select new{

                RiskChanceName = m.RiskChance.Name,
                m.DateCreated,
                m.Updated,
                m.TargetUpdated,
                m.Id,
                m.Description,
                m.DateShowDate,
                m.DateDetect,
                m.Summary,
                informed = m.RiskInformedUser + "(" + m.RiskInformedDep + ")",
                DamageTypeName = m.DamageType.Name,
                RiskReasonName = m.RiskReasonType.Name,
                RiskControlStatusName = m.RiskControlStatus.Name,
                RiskResponseStatusName = m.RiskResponseStatus.Name,
                m.RiskFormFillUser,
                RiskTutor = m.SystemUser.Name_Surname,
                RiskMasterName = m.RiskCompanyFullView.Name,
                m.RiskResultDescription,
                m.RiskPriseDamage,
                RiskResultName = m.RiskResult.Name,
                RiskTotalName = m.RiskTotalType.Name,
                m.RiskReason,
                m.RiskAdministrateSolution,
                m.RiskNote,
                m.RiskMaster,
                m.RegulatoryMaster,
                m.tblRegulatorDoer,
                RiskServiceName = m.RiskService.Name,                 
                m.WorkTime,
                link = "~/NoticeEditor.aspx?notice=" + m.Md5ash,
                            
           };*/
            GridView3.Visible = true;
            GridView3.DataSource = q;
            GridView3.DataBind();
        }
        else
        {
            GridView3.Visible = false;
        }


        db.Dispose();     
          
    }

 

SelectedIndex != 0 , tai tikrinu ar nera pirminis elementas, kurio value 0.

Viskas atrodytu kaip ir gerai (o gal galima su Linq kaip nors sujungt i viena tas uzklausas, cia greciausias variantas kuris man atejo i galva), bet jei as bandau paimti select new {} tai ant sitos vietos gaunu errorá - object reference is set null object ar pns.  Kas idomiausia, kad lygiai tokiu pat principu (tik nefiltruojant) isvedu i kita grid'a duomenis - viskas tvarkoje. Ar gali kad tokiu mano budu filtruojant kazkur sarysiai dingsta? O gal kur klaida ivelta, gal kas geriau pastebit nei as :)

 

Is anksto aciu uz patarimus