Question

我正在创建一个包含2个下拉列表的网站，一个连接到显示所有产品名称的数据源，第二个显示所有客户的公司名称（northwind）。

选择了两个选项后，会出现一个按钮，显示一个gridview，显示orderid，orderdate，shipdate和quantity，如果有来自该客户的订单（dropdownlist2），他们订购了该产品（dropdownlist1），否则我如果没有发生这种情况，将设置验证器。

我不明白的是如何让第3个数据源的SQL变得动态，因为它需要使用2个下拉列表中的内容作为条件。到目前为止，这就是我所拥有的：

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
    GridView1.Visible = True

    Dim v1, v2 As String
    v1 = DropDownList1.SelectedItem.Value.ToString
    v2 = DropDownList2.SelectedItem.Value.ToString

    SqlDataSource3.SelectCommand = "select O.OrderID, OrderDate, ShippedDate, Quantity" _
                                 & "from Orders O, [Order Details] D, Customers C, Products P" _
                                 & "where O.OrderID = D.OrderID" _
                                 & "and C.CustomerID = O.CustomerID" _
                                 & "and P.ProductID = D.ProductID" _
                                 & "and companyname = '" & v1 & "'" _
                                 & "and productname = '" & v2 & "'"

End Sub

很抱歉，如果我发生了所有这些错误，这是我第一次使用StackOverflow

Answer 1

请遵循此示例，假设ddlTwo依赖于ddlOne而GridView gv依赖于DropDownLists的选择：

Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init
    If Not IsPostBack Then
        ddlOne.DataBind()
        ddlTwo.DataBind()
    End If
End Sub

Protected Sub ddlOne_DataBinding(sender As Object, e As EventArgs) Handles ddlOne.DataBinding
    sender.DataSource = someListOne
    sender.DataTextField = "TXT"
    sender.DataValueField = "ID"
End Sub

Protected Sub ddlTwo_DataBinding(sender As Object, e As EventArgs) Handles ddlTwo.DataBinding
    sender.DataSource = someListTwo
    sender.DataTextField = "TXT"
    sender.DataValueField = "ID"
End Sub

Protected Sub ddlOne_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlOne.SelectedIndexChanged
    ddlTwo.DataBind()
    gv.DataBind()
End Sub

Protected Sub ddlTwo_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlTwo.SelectedIndexChanged
    gv.DataBind()
End Sub

Protected Sub gv_DataBinding(sender As Object, e As EventArgs) Handles gv.DataBinding
    sender.DataKeyNames = {"ID"}
    sender.DataSource = GetDataSource(ddlOne.SelectedValue, ddlTwo.SelectedValue)
End Sub

另外，如用户2615302所述，将AutoPostBack选项设置为True

Answer 2

设置你的DropDownList1 AutoPostBack =“True” 我的猜测他们没有价值

尝试在Sql查询中调试wuth断点并查看查询的值是什么

如何使用ASP.NET中相互依赖的多个数据源？

2 个答案: