如何将 OrderBy 应用于选择列表的 Linq 查询答案

【问题标题】：How do I apply OrderBy to a Linq Query for a select list如何将 OrderBy 应用于选择列表的 Linq 查询
【发布时间】：2014-05-08 21:41:15
【问题描述】：

我一定遗漏了一些明显的东西。此查询中的 orderby 子句对我的选择列表中显示的项目的顺序没有影响...

List<String> reps = (from r in db.bookings
                     where !r.bookingRep1.Contains("*") && !r.bookingRep1.Contains(" ")
                     orderby r.bookingRep1
                     select r.bookingRep1).Distinct().ToList();

ViewBag.rep1 = new SelectList(reps, booking.bookingRep1);

选择列表...

@Html.DropDownListFor(model => model.bookings.bookingRep1, (SelectList)ViewBag.rep1, "")

我希望选择列表按 bookingrep1 的字母顺序排列

【问题讨论】：

标签： asp.net-mvc linq entity-framework razor

【解决方案1】：

在应用Distinct:

之后应用订购

List<string> reps = 
   (from r in db.bookings 
    where !r.bookingRep1.Contains("*") && !r.bookingRep1.Contains(" ") 
    select r.bookingRep1).Distinct().OrderBy(rep => rep).ToList();

ViewBag.rep1 = new SelectList(reps, booking.bookingRep1);

当您将Distinct 应用于有序查询时，则刚刚从生成的 SQL 中删除了排序：

SELECT
    [Distinct1].[bookingRep1] AS [bookingRep1]
    FROM ( SELECT DISTINCT
        [Extent1].[bookingRep1] AS [bookingRep1]
        FROM [dbo].[bookings] AS [Extent1]
        WHERE [Extent1].[bookingRep1] NOT LIKE @p1 AND 
              [Extent1].[bookingRep1] NOT LIKE @p2
    )  AS [Distinct1]

当在Distinct 之后应用排序时，它会出现在生成的 SQL 中：

SELECT
    [Distinct1].[bookingRep1] AS [bookingRep1]
    FROM ( SELECT DISTINCT
        [Extent1].[bookingRep1] AS [bookingRep1]
        FROM [dbo].[bookings] AS [Extent1]
        WHERE [Extent1].[bookingRep1] NOT LIKE @p1 AND 
              [Extent1].[bookingRep1] NOT LIKE @p2
    )  AS [Distinct1]
    ORDER BY [Distinct1].[bookingRep1] ASC

【讨论】：

完美！谢谢谢尔盖！