Linq 中join实现多条件左连接

例子如下：

public dynamic GetPersonByDirector(string directorCode,int assessCycle)
        {
            var query = from person in container.T_BASE_PERSON
                        join plan in container.T_PLAN_PLAN on
                            new {PERSON_ID = person.ID, ASSESS_CYCLE = (int?) assessCycle} equals
                            new {plan.PERSON_ID, plan.ASSESS_CYCLE} into temp
                        from personPlan in temp.DefaultIfEmpty()
                        join assessinfo in container.T_BASE_ASSESSINFO on person.ID equals assessinfo.PERSON_ID
                        join org in container.T_BASE_ORG on assessinfo.DEPT_ORG_CODE equals org.ORG_CODE
                        where assessinfo.DIRECTORS_ID.Contains(directorCode) && assessinfo.ASSESS_CYCLE == assessCycle
                        select new
                                   {
                                       PERSON_CODE = person.PERSON_CODE,
                                       PERSON_NAME = person.PERSON_NAME,
                                       ORG_NAME = org.ORG_NAME,
                                       STATUS = personPlan == null ? -1 : personPlan.STATUS,
                                       //左连接，可能为空，下同
                                       ID = person.ID,
                                       PLAN_ID = personPlan == null ? 0 : personPlan.ID
                                   };
            return query.AsQueryable();
        }

如代码中红色标红所示。