public List<TaskRoutineGridData> GetDataList(string ComId, string TaskRoutineId)
{
List<TaskRoutineGridData> item;

        try
        {

            var query = from f in db.ProductionLand.Where(a => a.EnterpriseId == ComId && a.IsActive == 1)
                      
                        join a in db.TaskRoutine.Where(a => a.EnterpriseId == ComId && a.IsFinish == 0) on f.LandId equals a.LandId into temp
                        from a in temp.DefaultIfEmpty()
                        join c in db.ProductInfo on a.EntityProductId equals c.ProductId into temp1
                        from c in  temp1.DefaultIfEmpty()
                        select new TaskRoutineGridData
                        {
                            LandId = f.LandId,
                            EntityProductName = c.ProductName,
                            LandName = f.LandName,
                            ProductionType = f.ProductionType,
                            TaskRoutineId = a.TaskRoutineId,
                        };
          
            item = query.ToList();
        }
        catch (Exception ex)
        {
            throw new Exception(ex.Message);
        }
        return item;
    }

这是我写好的方法，现在根据LandName分类展示ProductName，实现上面那个效果