Question

我在Linq-to-entities（4.0）中创建了一个查询，让我感到困惑，因为我加入了几个表，其中两个共享一个列名（DateCreated）。当我尝试在具有相同列名的两个表之间使用orderby时，我得到以下错误：'order'DateCreated'在order子句中是不明确的'

我很困惑，因为我认为指定表意味着它会将其传递给SQL查询。在下面的示例中，我指定'orderby a.Datecreated'，但在TSQL中它只有ORDER BY DateCreated，当我希望看到ORDER BY Extent1。DateCreated时。

using (PDFActionsEntities pdfEntities = new PDFActionsEntities())
{
    var actions = (from a in pdfEntities.PDFActions
               join f in pdfEntities.Files on a.FileID equals f.FileID into list1
               from l1 in list1.DefaultIfEmpty()
               join wp in pdfEntities.WebPages on a.WebPageID equals wp.webpageid into list2
               from l2 in list2.DefaultIfEmpty()
               orderby a.DateCreated
               select new
               {
                   ID = a.ID,
                   FileID = a.FileID,
                   WebPageID = a.WebPageID,
                   UserID = a.UserID,
                   FilePath = l1.Path,
                   URLPath = l2.url,
                   DateCreated = a.DateCreated
               });

}

这是它创建的T-SQL

SELECT
`Extent1`.`FileID`, 
`Extent1`.`ID`, 
`Extent1`.`WebPageID`, 
`Extent1`.`UserID`, 
`Extent2`.`Path`, 
`Extent3`.`url`, 
`Extent1`.`DateCreated`
FROM `tblpdfactions` AS `Extent1` LEFT OUTER JOIN
 `tblfiles` AS `Extent2` ON `Extent1`.`FileID` = `Extent2`.`FileID` LEFT OUTER JOIN 
`tblwebpageprints` AS `Extent3` ON `Extent1`.`WebPageID` = `Extent3`.`webpageid`
ORDER BY `DateCreated` ASC

我错过了什么或做错了什么？

P.S。如果这有任何区别，它就连接到MySQL。

编辑：

在我提出问题之后，我看到另一个基于左连接的问题，这导致我写道：

var actions = (from a in pdfEntities.PDFActions
           join f in pdfEntities.Files on a.FileID equals f.FileID into list1
           from l1 in list1.DefaultIfEmpty()
           join wp in pdfEntities.WebPages on a.WebPageID equals wp.webpageid into list2
           from l2 in list2.DefaultIfEmpty()
           select new 
           {
               ID = a.ID,
               FileID = a.FileID,
               WebPageID = a.WebPageID,
               UserID = a.UserID,
               FilePath = l1.Path,
               URLPath = l2.url,
               DateCreated = a.DateCreated
           }).OrderBy(x => x.DateCreated);

我在select new上添加了Orderby。这现在有效。但是，我仍然很困惑为什么当orderby在主查询中时它不会做同样的事情。嘿嘿！有点烦人，我在这几天花了大约5个小时，在发布的几秒钟内，我找到了答案！

Answer 1

您是否尝试将orderby移至select关键字后的查询末尾？像：

actions.OrderBy(a => a.DateCreated);

Answer 2

有可能将TSQL生成为特定select新语句的部分构造。您是否尝试将属性的名称更改为不同的名称：

select new
{
    ID = a.ID,
    FileID = a.FileID,
    WebPageID = a.WebPageID,
    UserID = a.UserID,
    FilePath = l1.Path,
    URLPath = l2.url,
    Created = a.DateCreated  // Change is here
}

Linq-to-entities orderby给出了不明确的列名错误

2 个答案: