linq在子查询中有最大日期

Posted 2021-03-27

我需要选择一个连接到具有status和插入DateTime的另一个表的记录。我希望与AgreementStatuses对应的记录具有最大Date_Created

from c in Agreements 
    join a in AgreementStatuses on c.Agreements_ID equals a.Agreements_ID
    join s in Statuses on a.Statuses_ID equals s.Statuses_ID
where DateTime.Now > c.BeginDate
    && DateTime.Now < c.TermDate
    && c.ControlPlan_ID == 31
    && s.StatusText == "Promoted"
    && c.AlphaPrefix == "PEH"
    && c.States_ID == 33
    && a.Date_Created == (from n in AgreementStatuses  //ERROR HERE
        join y in Statuses on n.Statuses_ID equals y.Statuses_ID
        where y.StatusText == "Promoted"
        && n.Agreements_ID == 584
        group n by n.Agreements_ID into g
        select new {Date_Created = g.Max(t=>t.Date_Created)}).FirstOrDefault()
select c

错误：

Operator '==' cannot be applied to operands of type 'DateTime' and '<anonymous type: DateTime Date_Created>'

答案

谢谢jdweng。这样做了。

from c in Agreements 
    join a in AgreementStatuses on c.Agreements_ID equals a.Agreements_ID
    join s in Statuses on a.Statuses_ID equals s.Statuses_ID
where DateTime.Now > c.BeginDate
    && DateTime.Now < c.TermDate
    && c.ControlPlan_ID == 31
    && s.StatusText == "Promoted"
    && c.AlphaPrefix == "PEH"
    //&& c.States_ID == 33
    && a.Date_Created == (from n in AgreementStatuses 
        join y in Statuses on n.Statuses_ID equals y.Statuses_ID
        where y.StatusText == "Promoted"
        && n.Agreements_ID == a.Agreements_ID
        group n by n.Agreements_ID into g
        select g.Max(t=>t.Date_Created)).FirstOrDefault()
select c