Linq进行多项选择

问题描述

朋友们，
我需要Linq查询才能从3个表中选择数据.

我用C#代码实现.但是我需要在LINQ Query中进行开发.

foreach(dtChapter.Rows中的DataRow drChapters)
{
DataRow dr = dtPlanInfo.NewRow();
foreach(dtMileStones.Rows中的DataRow drMileStone)
{
dr ["Chapter"] = drChapters ["Chapter"].ToString();
DataRow [] drStages = dtStages.Select("Chapter =""+ drChapters [" Chapter].ToString()+"''和MilestoneDesc =" + drMileStone ["MilestoneDesc"] +''")；
foreach(drStages中的DataRow drs)
{
dr [drMileStone ["MilestoneDesc"].ToString()+"PlanDate"] = drs ["PlanDate"];
dr [drMileStone ["MilestoneDesc"].ToString()+"ActualDate"] = drs ["ActualDate"];
dr [drMileStone ["MilestoneDesc"].ToString()+"Remarks"] = drs ["Remarks"].ToString();
dr [drMileStone ["MilestoneDesc"].ToString()+"RevisedCount"] = drs ["RevisedCount"];
dr [drMileStone ["MilestoneDesc"].ToString()+"LastTimeRevised"] = drs ["LastRevisedPlanDate"];
}
}
dtPlanInfo.Rows.Add(dr);
}

涉及的表是

第

Ch1

Ch2

MileStone

MileStoneDesc

M1

M2

StageId	PlanDate	ActualDate	备注	第	MilestoneDesc	revisedCount	LastTimeRevised
1	12/9/2012	2012/12/15	test	Ch1	M1
2	3/2/2013	5/6/2013	test2	ch2	M2

我需要结果为

章节	M1Plan	M1Actual	M1Remark	M1RevisedCount	M1LastRevised	M2Plan	M2Actual	M2Remark	M2RevisedCount	M2LastRevised
ch1	2012/12/9	2012/12/15		test
ch2						3/2/2013	5/6/2013	test2

请提供Linq查询以获取此结果.

Hi friends,
i need the Linq Query to select datas from 3 Tables.

I acheived in c# Code. But i need to develop in LINQ Query.

foreach (DataRow drChapters in dtChapter.Rows)
{
DataRow dr = dtPlanInfo.NewRow();
foreach (DataRow drMileStone in dtMileStones.Rows)
{
dr["Chapter"] = drChapters["Chapter"].ToString();
DataRow[] drStages = dtStages.Select("Chapter=''" + drChapters["Chapter"].ToString() + "'' and MilestoneDesc=''" + drMileStone["MilestoneDesc"] + "''");
foreach (DataRow drs in drStages)
{
dr[drMileStone["MilestoneDesc"].ToString() + "PlanDate"] = drs["PlanDate"];
dr[drMileStone["MilestoneDesc"].ToString() + "ActualDate"] = drs["ActualDate"];
dr[drMileStone["MilestoneDesc"].ToString() + "Remarks"] = drs["Remarks"].ToString();
dr[drMileStone["MilestoneDesc"].ToString() + "RevisedCount"] = drs["RevisedCount"];
dr[drMileStone["MilestoneDesc"].ToString() + "LastTimeRevised"] = drs["LastRevisedPlanDate"];
}
}
dtPlanInfo.Rows.Add(dr);
}

The Tables involved are

Chapter

Ch1

Ch2

MileStone

MileStoneDesc

M1

M2

StageId	PlanDate	ActualDate	Remarks	Chapter	MilestoneDesc	revisedCount	LastTimeRevised
1	12/9/2012	15/12/2012	test	Ch1	M1
2	3/2/2013	5/6/2013	test2	ch2	M2

I need the Result as

Chapter	M1Plan	M1Actual	M1Remark	M1RevisedCount	M1LastRevised	M2Plan	M2Actual	M2Remark	M2RevisedCount	M2LastRevised
ch1	12/9/2012	15/12/2012		test
ch2						3/2/2013	5/6/2013	test2

Please provide me the Linq Query to get this result.

推荐答案

IEnumerable<dataset1.dtplaninforow> planInfos = DataSetInstance.dtStages.AsEnumerable()
    .Where(st =>
        DataSetInstance.dtChapter.Any(ch => ch.Chapter==st.Chapter) &&
        DataSetInstance.dtMileStones.Any(ms => ms.MilestoneDesc==st.MilestoneDesc))
    .Select(st => {
        var dr = DataSetInstance.dtPlanInfo.NewdtPlanInfoRow();
        dr.Chapter = st.Chapter;
        dr[string.Format("{0}Plan", st.MilestoneDesc)] = st.PlanDate;
        dr[string.Format("{0}Actual", st.MilestoneDesc)] = st.ActualDate;
        dr[string.Format("{0}Remark", st.MilestoneDesc)] = st.Remarks;
        dr[string.Format("{0}RevisedCount", st.MilestoneDesc)] = st.revisedCount;
        dr[string.Format("{0}LastRevised", st.MilestoneDesc)] = st.LastTimeRevised;
        return dr;
    });
planInfos.CopyToDataTable(DataSetInstance.dtPlanInfo, LoadOption.PreserveChanges);

在PlanInfo 表的新行中设置值时，使用LINQ query expression syntax很难获得上述结果.

It is somewhat difficult to get the above result using the LINQ query expression syntax in setting the values in new row of PlanInfo table.

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