Linq子查询Where子句

我需要一些关于thsi linq查询的帮助。这应该是相当简单的，但它是踢我的屁股

我需要使用子查询从主查询中筛选出数据，但我尝试使用的每个路径都会导致失败

子查询本身如下所示。

int pk = (from c in context.PtApprovedCertifications
         where c.FkosParticipant == 112118 &&
         (!excludedActionTypes.Contains(c.FkMLSosCodeActionType)) &&
         c.EffectiveDate <= DateTime.Now &&
         c.FkptApprovedCertificationVoidedBy == null
         orderby c.EffectiveDate descending,c.PK descending
         select c.PK).FirstOrDefault();

IQueryable<PtAMember> result = (from p in context.PtAMembers
    where (p.FkptACertification == (from c in context.PtApprovedCertifications
        where c.FkosParticipant == p.PtApprovedCertification.OsParticipant.PK &&
        (!excludedActionTypes.Contains(c.FkMLSosCodeActionType)) &&
        c.EffectiveDate <= DateTime.Now &&
        c.FkptApprovedCertificationVoidedBy == null
        orderby c.EffectiveDate descending, c.PK descending
        select c.PK).FirstOrDefault()) &&
            (p.LastName.ToLower().Contains(param.ToLower()) ||
            p.FirstName.ToLower().Contains(param.ToLower()) ||
            p.SocialSecurityNumber.Contains(param))
    select p).Distinct().OrderBy(PtAMembers => PtAMembers.LastName).ThenBy(PtAMember => PtAMember.FirstName);

int pk=（来自context.PtApprovedCertifications中的c
其中c.FkosParticipant==112118&&
（！excludedActionTypes.Contains（c.fkmlsocodeActionType））&&
c、 EffectiveDate如何将子查询转换为查找函数：

Func<int, int> pkLookup = n => (from c in context.PtApprovedCertifications
                      where c.FkosParticipant == n &&
                      (!excludedActionTypes.Contains(c.FkMLSosCodeActionType)) &&
                      c.EffectiveDate <= DateTime.Now &&
                      c.FkptApprovedCertificationVoidedBy == null
                      orderby c.EffectiveDate descending,c.PK descending
                      select c.PK).FirstOrDefault();

Func pkLookup=n=>（来自context.PtApprovedCertifications中的c
其中c.FkosParticipant==n&&
（！excludedActionTypes.Contains（c.fkmlsocodeActionType））&&
c、 EffectiveDate错误消息说什么？我尝试了你的解决方案Jerome，下面是我得到的错误。我应该提到我使用Telerik OpenAccess作为我的ORM，并且在他们的站点上有一个类似的线程，因为这可能不是LINQ问题，而是OpenAccess问题。错误消息-调用参数不是参数表达式会话参数名称：invocationExpression实际值为Invoke（值（EliteXtender.EliteDataService.Domain.Residents+c_uDisplayClass3）。pkLookup，p.PtApprovedCertification.OsParticipant.PK）。StackTrace-at Telerik.OpenAccess.Query.ExpressionCompiler.PerformDatabaseQueryImpl（类型，Int32 elementAt，Object[]groupResolutionParamValues）位于Telerik.OpenAccess.Query.ExpressionCompiler.PerformDatabaseQuery（类型类型，Int32 elementAt，对象[]groupResolutionParamValues）