在join linqc#中获取最新的记录

本文关键字：最新 记录 获取 join linqc# | 更新日期: 2023-09-27 18:05:25

我有这个查询

return from fitUpExaminationDetails in _ctx.FitUpExaminationDetails
                where fitUpExaminationDetails.FitUpExaminationId == Id
                join joint in _ctx.Joints on fitUpExaminationDetails.JointId equals joint.Id
                join line in _ctx.Lines on joint.LineId equals line.Id
                join fileIsoManager in _ctx.FileIsoManagers on line.Id equals fileIsoManager.LineId
                select new ViewDomainClass.QualityControl.Report.ViewFitupExaminationReport
                {
                    HeatNumber1 = fitUpExaminationDetails.HeatNumber1,
                    HeatNumber2 = fitUpExaminationDetails.HeatNumber2,
                    JointNumber = joint.JointNumber,
                    LineNumber = line.LineNumber,
                    Revision = fileIsoManager.Revision,            
                };

我的line表可以有多个fileIsoManager记录。所以在选择语句中，我的意思是在这部分Revision = fileIsoManager.Revision中，我想显示fileIsoManager表中的最新记录。我怎么能改变这个查询呢?

在join linqc#中获取最新的记录

好吧，因为你没有提供太多的细节，我写了几个类来告诉你如何获得你的最新版本的每一行。注意"main"函数

// These are a representation of your classes :
public class Line
{
    public int LineId { get; set; }
    public string SomeValue { get; set;}
}
public class Revision
{
    public int RevisionId { get; set; }
    public int LineId { get; set;}  
}
void Main()
{
    // generating some data so we can test the query.
    var lines = new List<Line>() { 
        new Line() { LineId = 1, SomeValue = "Allo!" } 
        };
    var revisions = new List<Revision>() { 
        new Revision() { LineId = 1, RevisionId = 1 }, 
        new Revision() { LineId = 1, RevisionId = 2 }, 
        new Revision() { LineId = 1, RevisionId = 3 }
        };

    var result = (
        from line in lines
        join revision in revisions on line.LineId equals revision.LineId
        group revision by line into grp
        select new
        {
            Line = grp.Key,
            LastRevision = grp.OrderByDescending(rev => rev.RevisionId).FirstOrDefault()
        }
        ).ToList();
}

所以，基本上，你需要按行分组你的修订。在选择部分，您可以获得每行的最新版本。

在本例中，result将包含一个动态对象，该对象包含行id=1和版本id= 3。

回到你的查询，它应该看起来像这样得到一个类似的结果:

return 
    from fitUpExaminationDetails in _ctx.FitUpExaminationDetails
    where fitUpExaminationDetails.FitUpExaminationId == Id
    join joint in _ctx.Joints on fitUpExaminationDetails.JointId equals joint.Id
    join line in _ctx.Lines on joint.LineId equals line.Id
    join fileIsoManager in _ctx.FileIsoManagers on line.Id equals fileIsoManager.LineId
    group fileIsoManager by new { fitUpExaminationDetails, joint, line} into grp
    select new ViewDomainClass.QualityControl.Report.ViewFitupExaminationReport
    {
       HeatNumber1 = grp.Key.fitUpExaminationDetails.HeatNumber1,
       HeatNumber2 = grp.Key.fitUpExaminationDetails.HeatNumber2,
       JointNumber = grp.Key.joint.JointNumber,
       LineNumber = grp.Key.line.LineNumber,
       Revision = grp.OrderByDescending(fileIsoMgr => gileIsoMgr.Id).FirstOrDefault()
    };
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