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select{}中的Linq order by集合

linq-to-sql c#

Joe Pitz · 技术社区 · 16 年前

下面是我正在研究的一个:

var fStep =
            from insp in sq.Inspections
            where insp.TestTimeStamp > dStartTime && insp.TestTimeStamp < dEndTime
                && insp.Model == "EP" && insp.TestResults != "P"
            group insp by new { insp.TestResults, insp.FailStep } into grp

            select new
            {
                FailedCount = (grp.Key.TestResults == "F" ? grp.Count() : 0),
                CancelCount = (grp.Key.TestResults == "C" ? grp.Count() : 0),
                grp.Key.TestResults,
                grp.Key.FailStep,
                PercentFailed = Convert.ToDecimal(1.0 * grp.Count() /tcount*100)

            } ;

我想按选择投影中的一个或多个字段排序。

3 回复 | 直到 16 年前

Jon Skeet 16 年前

最简单的更改可能是使用查询延续:

var fStep =
        from insp in sq.Inspections
        where insp.TestTimeStamp > dStartTime && insp.TestTimeStamp < dEndTime
            && insp.Model == "EP" && insp.TestResults != "P"
        group insp by new { insp.TestResults, insp.FailStep } into grp
        select new
        {
            FailedCount = (grp.Key.TestResults == "F" ? grp.Count() : 0),
            CancelCount = (grp.Key.TestResults == "C" ? grp.Count() : 0),
            grp.Key.TestResults,
            grp.Key.FailStep,
            PercentFailed = Convert.ToDecimal(1.0 * grp.Count() /tcount*100)

        } into selection
        orderby selection.FailedCount, selection.CancelCount
        select selection;

老实说,这相当于使用“let”,真正的区别是let引入了范围变量,而查询继续有效地启动了范围变量的新范围-您不能引用 grp 后位内 into selection 例如。

值得注意的是,这是 确切地

var unordered =
        from insp in sq.Inspections
        where insp.TestTimeStamp > dStartTime && insp.TestTimeStamp < dEndTime
            && insp.Model == "EP" && insp.TestResults != "P"
        group insp by new { insp.TestResults, insp.FailStep } into grp
        select new
        {
            FailedCount = (grp.Key.TestResults == "F" ? grp.Count() : 0),
            CancelCount = (grp.Key.TestResults == "C" ? grp.Count() : 0),
            grp.Key.TestResults,
            grp.Key.FailStep,
            PercentFailed = Convert.ToDecimal(1.0 * grp.Count() /tcount*100)

        };

var fStep = from selection in unordered
            orderby selection.FailedCount, selection.CancelCount
            select selection;

David Fox 16 年前

.OrderBy(x => x.FailedCount).ThenBy(x => x.CancelCount);

Matthew Whited 16 年前

您可以将select值移动到let赋值,然后在此之后构建order by。

var fStep =
    from insp in sq.Inspections
    where insp.TestTimeStamp > dStartTime && insp.TestTimeStamp < dEndTime
       && insp.Model == "EP" && insp.TestResults != "P"
    group insp by new { insp.TestResults, insp.FailStep } into grp
    let newInsp = new
    {
        FailedCount = (grp.Key.TestResults == "F" ? grp.Count() : 0),
        CancelCount = (grp.Key.TestResults == "C" ? grp.Count() : 0),
        grp.Key.TestResults,
        grp.Key.FailStep,
        PercentFailed = Convert.ToDecimal(1.0 * grp.Count() / tcount * 100)

    }
    orderby newInsp.FailedCount, newInsp.CancelCount
    // or this ...
    //orderby newInsp.FailedCount
    //orderby newInsp.CancelCount
    select newInsp;
;