使用 UNION 的 LINQ-TO-XML

Question

我正在尝试联合查询来创建 XML 文件。查询本身作为 T-SQL 工作，但我作为 LINQ-TO-XML 的实现失败，并出现“无法翻译表达式...”错误。

我问错问题了吗？这种做法完全错误吗？我是 LINQ 新手。如何从 2 个查询创建单个 XML？

Dim db As New SOMEDataContext

Dim members As New XElement("members", _
    (From c In db.Employees _
    Join cf In db.BowlingTeams On c.ID Equals cf.BowlingTeam_Text _
        Where c.DEPARTMENT = "Housewares" _
            Select New XElement("member", _
                New XElement("id", c.ID), _
                New XElement("title", c.TITLE))) _
    .Union(From e In db.Employees _
        Where e.DEPARTMENT = "Housewares" _
        Where e.POSITION Like "*XYZ*" _
            Select New XElement("member", _
                New XElement("id", e.ID), _
                New XElement("title", e.TITLE))))

Answer 1

下面是我在 VB 中执行此操作的方法：

    Dim members = <members>
                      <%= From c In db.Employees _
                          Join cf In db.BowlingTeams On c.ID Equals cf.BowlingTeam_Text _
                          Where c.DEPARTMENT = "Housewares" _
                          Select <member>
                                     <id><%= c.ID %></id>
                                     <title><%= c.TITLE %></title>
                                 </member> %>
                      <%= From e In db.Employees _
                          Where e.DEPARTMENT = "Housewares" _
                          Where e.POSITION Like "*XYZ*" _
                          Select <member>
                                     <id><%= e.ID %></id>
                                     <title><%= e.TITLE %></title>
                                 </member> %>
                  </members>

这利用了 XML Literals，从而避免了所有 New XElement 调用。

Answer 2

我认为你只需要做这样的事情。不确定 VB 语法是否正确。

   Dim query As From c In db.Employees Join cf In db.CourseFaculties On c.ID Equals cf.COURSEFACULTY_Text Where c.DEPARTMENT = "Housewares" Select New XElement("member", _
       New XElement("id", c.ID), New XElement("title", c.TITLE))).Union(From e In db.DATATEL_Employees Where e.DEPARTMENT = "Housewares" Where e.POSITION Like "*XYZ*" _
       Select New XElement("member", New XElement("id", e.ID), New XElement("title", e.TITLE)));

   Dim members As New XElement("members");
   foreach (XElement result in query)
       members.Add(result);