C# dynamic linq query

In to Linq query, we can use dynamic query:

  public List<Insplan> GetInsplanLookupList(string planName = null, string binNo = null, string procCtrl = null)  
     {  
       var query = (from i in _db.insplan  
              orderby i.cinsplanname ascending  
              select i).AsQueryable();  
       if (!string.IsNullOrWhiteSpace(planName))  
         query = query.Where(x => x.cinsplanname.StartsWith(planName.Trim()));  
       if (!string.IsNullOrWhiteSpace(binNo))  
         query = query.Where(x => x.cbinno.StartsWith(binNo.Trim()));  
       if (!string.IsNullOrWhiteSpace(procCtrl))  
         query = query.Where(x => x.cprocctrlno.StartsWith(procCtrl.Trim()));  
       return (from q in query  
           join ic in _db.inscomp on q.inscompid_FK equals ic.inscompid_PK into ic_joined  
           from ic in ic_joined.DefaultIfEmpty()  
           join cl in _db.clinic on q.clinicid_FK equals cl.clinicid_PK into cl_joined  
           from cl in cl_joined.DefaultIfEmpty()  
           join b in _db.insbiller on q.insbillerid_FK equals b.insbillerid_PK into gj  
           from sub in gj.DefaultIfEmpty()  
           select new Insplan  
           {  
             insplanid_PK = q.insplanid_PK,  
             cinsplanname = q.cinsplanname,  
             cbinno = q.cbinno,  
             cpharmacyno = q.cpharmacyno,  
             cprocctrlno = q.cprocctrlno,  
             ncpdpversion_FK = q.ncpdpversion_FK,  
             cinscompname = ic.cinscompname,  
             cinsbillername = sub.cinsbillername,  
             Inscomp = (ic != null ? new Inscomp { cinscompname = ic.cinscompname, inscompid_PK = ic.inscompid_PK } : null),  
             Clinic = (cl != null ? new Clinic { clinicid_PK = cl.clinicid_PK, cclinicname = cl.cclinicname } : null)  
           }).Take(20).ToList();  
     }