Question

我的数据库中有两个表，Building和Rooms。我正在使用两个下拉列表。目的是获得第一个下拉列表ddlBuilding，用于选择建筑物名称。选择名称后，我想查询数据库，只查找与该建筑物对应的房间号，并在房间下拉列表ddlRoomNumber中返回。例如：

A楼有1号房，2号房和3号房 B楼有4号，5号和6号房间。

如果用户从ddlBuilding中选择了建筑物A，则只能在ddlRoomNumber

中显示房间1,2和3

我已经设置了一个查询来执行此操作但我收到一个错误，说dropdownlist无法转换为字符串。有问题的代码是：

  Protected Sub txtRoomNumber_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtRoomNumber.TextChanged

    Dim db As New OrionDataClassesDataContext

    Dim roomNumber = (From build In db.Buildings Join rm In db.Rooms On build.Building_code Equals rm.Building_code
                      Where build.Building_name = ddlBuilding
                      Select rm.Room_Number).distint

    ddlRoomNumber.DataSource = roomNumber
    ddlRoomNumber.DataBind()

End Sub

导致错误的是行where build.Building_name = ddlBuilding。关于如何将字符串拉出下拉列表并使用它来验证我的查询的任何想法。

在一些回复和研究之后，我已将代码更改为以下内容。它仍然无法正常工作。 ddlRoomNumber未绑定到我的查询。

Protected Sub ddlRoomNumber_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlRoomNumber.SelectedIndexChanged

    Dim db As New OrionDataClassesDataContext


    ddlRoomNumber.DataSource = (From build In db.Buildings Join rm In db.Rooms On build.Building_code Equals rm.Building_code
                                Where (build.Building_name = ddlBuilding.SelectedItem.Text)
                                Select rm.Room_Number, rm.Room_ID)

    ddlRoomNumber.DataTextField = "Room_Number"
    ddlRoomNumber.DataValueField = "Room_ID"
    ddlRoomNumber.DataBind()
End Sub

这是asp页面。有没有办法输入linq数据源来指向我的vb查询。

<asp:DropDownList ID="ddlRoomNumber" runat="server" AutoPostBack="True">
                           </asp:dropdownlist>

Answer 1

您可以使用ddlBuilding.SelectedItem.Text代替ddlBuilding

将dropdownlist值转换为字符串

1 个答案: