EF 筛选列包含NULL会报错

 当PlanNO 为空时，我们在EF查询筛选PlanNO列时，会报错

          Expression<Func<DeliveryPlan, bool>> expr = PredicateExtensionses.True<DeliveryPlan>(); //动态拼接查询 //静态类的使用步骤          
            expr.And(c => c.IsDel == 1);
            if (!kname.IsEmpty())//出货计划单号查询  这里PlanNO
            {
                expr = expr.And(c => c.PlanNO.ToUpper().Contains(kname));
            }
            if (!number.IsEmpty())//制单日期查询
            {
                expr = expr.And(c => c.MakeDate >= Convert.ToDateTime(number));
            }
            if (!numbers.IsEmpty()) //制单日期查询
            {
                expr = expr.And(c => c.MakeDate <= Convert.ToDateTime(numbers));
            }
            if (!idesd.IsEmpty())  //Isdel的默认值
            {
                expr = expr.And(c => c.IsDel == idesd.AsInt());
            }
            if (!numes.IsEmpty())  //下拉列表值
            {
                expr = expr.And(c => c.IsAudit == numes.AsInt());
            }
            if (!numvves.IsEmpty())
            {
                expr = expr.And(c => c.Achieve == numvves.AsInt());
            }
            var qury = getpagelistdata.GetPageList<XTAPP.Models.DeliveryPlan, object>(page, pagesize, out totalcount, expr.Compile(), c => c.ID); //查询到集合数据

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解决方法可以把PlanNO的NULL改为空