Question

我试图制作两个将从数据库填充的下拉列表。出于某种原因，它说我的VB.net代码中的下拉列表没有声明。它应该从ASP代码中声明AcadYrDDL和TermDDL吗？

我是asp和vb.net的新手;需要一些帮助。而且，如果你们能指出我所犯的某些错误，那就太好了。

ASP：

    <asp:DropDownList runat="server" id="AcadYrDDL" AppendDataBoundItems="true">
        <asp:ListItem Text="option" Value=""/>
    </asp:DropDownList>
    <asp:DropDownList runat="server" id="TermDDL" AppendDataBoundItems="true">
        <asp:ListItem Text="option" Value=""/>
    </asp:DropDownList>
    <asp:Button runat="server" type="button" id="viewButton" class="btn btn-default" value="View">
        <span class="glyphicon glyphicon-th-list" aria-hidden="true"></span>&nbsp View
    </asp:Button>
</form>

VB.NET：

Imports System.Configuration
Imports System.IO
Imports System.Data.SqlClient



Partial Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Populate1()
        Populate2()
    End Sub

    Public Sub Populate1()
        Dim cmd As New SqlCommand("SELECT term FROM CADETCRSE", New SqlConnection(ConfigurationManager.AppSettings("ConnString")))
        cmd.Connection.Open()

        Dim ddlValues As SqlDataReader
        ddlValues = cmd.ExecuteReader()

        AcadYrDDL.DataSource = ddlValues
        AcadYrDDL.DataValueField = ""
        AcadYrDDL.DataTextField = "Acadyr"
        AcadYrDDL.DataBind()

        cmd.Connection.Close()
        cmd.Connection.Dispose()
    End Sub

    Public Sub Populate2()
        Dim cmd As New SqlCommand("SELECT AcadYr FROM CADETCRSE", New SqlConnection(ConfigurationManager.AppSettings("ConnString")))
        cmd.Connection.Open()

        Dim ddlValues As SqlDataReader
        ddlValues = cmd.ExecuteReader()

        TermDDL.DataSource = ddlValues
        TermDDL.DataValueField = ""
        TermDDL.DataTextField = "Current term"
        TermDDL.DataBind()

        cmd.Connection.Close()
        cmd.Connection.Dispose()
    End Sub





End Class

Answer 1

DataValueField和DataTextField应该是数据库调用的字段。如果没有明确设置DataValueField，请保留它，不要尝试将其设置为空字符串。您的最终代码应如下所示：

Public Sub Populate1()
    Dim cmd As New SqlCommand("SELECT term FROM CADETCRSE", New SqlConnection(ConfigurationManager.AppSettings("ConnString")))
    cmd.Connection.Open()

    Dim ddlValues As SqlDataReader
    ddlValues = cmd.ExecuteReader()

    AcadYrDDL.DataSource = ddlValues
    AcadYrDDL.DataTextField = "term" 'This is the field in your database call
    AcadYrDDL.DataBind()

    cmd.Connection.Close()
    cmd.Connection.Dispose()
End Sub

Public Sub Populate2()
    Dim cmd As New SqlCommand("SELECT AcadYr FROM CADETCRSE", New SqlConnection(ConfigurationManager.AppSettings("ConnString")))
    cmd.Connection.Open()

    Dim ddlValues As SqlDataReader
    ddlValues = cmd.ExecuteReader()

    TermDDL.DataSource = ddlValues
    TermDDL.DataTextField = "AcadYr" 'As this is what you have returned in your 
    TermDDL.DataBind()

    cmd.Connection.Close()
    cmd.Connection.Dispose()
End Sub

未声明名称<name>

1 个答案: