如何选择与SqlDataSource的级联的DropDownList [英] How to select cascading DropDownList with SqlDataSource

问题描述

我在我的数据库如下 -

  breedId种品种
0阿尔萨斯狗
1狗比特犬
2犬喜乐蒂牧羊犬
3狗义和团
4猫李龙
5猫澳大利亚雾
6呵叻猫
 

在C＃的设计师认为，我有2个下拉列表中选择一个具有物种和其他的品种。

我要的是，：当用户在挑选物种名单狗，
该品种名单应具有以下阿尔萨斯，斗牛犬，喜乐蒂牧羊犬，拳师

目前，当我拿起狗，都可以通过数据库的品种所示。

 ＆LT; ASP：DropDownList的ID =DropDownListSpecies=服务器
     HEIGHT =27pxWIDTH =107px的DataSourceID =hs330
     DataTextField =种DataValueField =种＆GT;
＆LT; / ASP：DropDownList的＆GT;
＆LT; ASP：SqlDataSource的ID =种=服务器
     的ConnectionString =下;％$的ConnectionStrings：的ConnectionString％＆gt;中
     的SelectCommand =SELECT DISTINCT [种] FROM [品种]＆GT;
＆LT; / ASP：SqlDataSource的＆GT;＆LT; ASP：DropDownList的ID =DropDownListBreed=服务器HEIGHT =20像素
    WIDTH =110px的DataSourceID =繁殖DataTextField =繁殖
    DataValueField =品种＆GT;
＆LT; / ASP：DropDownList的＆GT;
＆LT; ASP：SqlDataSource的ID =繁殖=服务器
    的ConnectionString =下;％$的ConnectionStrings：的ConnectionString％＆gt;中
    的SelectCommand =SELECT DISTINCT [品种] FROM [品种]＆GT;
＆LT; / ASP：SqlDataSource的＆GT;
 

解决方案

您需要先使用 ControlParameter SelectParameters

请确保该的AutoPostBack =真对于 DropDownListSpecies

供参考：您有错字的 Speecies

 ＆LT; ASP：DropDownList的ID =DropDownListSpecies=服务器
    HEIGHT =27pxWIDTH =107px的DataSourceID =种
    DataTextField =种DataValueField =种的AutoPostBack =真＆GT;
＆LT; / ASP：DropDownList的＆GT;
＆LT; ASP：SqlDataSource的ID =种=服务器
    的ConnectionString =下;％$的ConnectionStrings：的ConnectionString％＆gt;中
    的SelectCommand =SELECT DISTINCT [种] FROM [品种]＆GT;＆LT; / ASP：SqlDataSource的＆GT;
＆LT; ASP：DropDownList的ID =DropDownListBreed=服务器
    HEIGHT =20像素WIDTH =110px
    的DataSourceID =繁殖DataTextField =品种DataValueField =品种＆GT;
＆LT; / ASP：DropDownList的＆GT;
＆LT; ASP：SqlDataSource的ID =繁殖=服务器
    的ConnectionString =下;％$的ConnectionStrings：的ConnectionString％＆gt;中
    的SelectCommand =SELECT DISTINCT [品种] FROM [品种] WHERE种= @种＆GT;
    ＆LT; SelectParameters＆GT;
        ＆LT; ASP：ControlParameter控件ID =DropDownListSpecies属性名=的SelectedValue
            NAME =种类型=字符串默认值=猫/＆GT;
    ＆LT; / SelectParameters＆GT;
＆LT; / ASP：SqlDataSource的＆GT;
 

I have the following in my data base -

breedId Species Breed
0       dog      Alsatian
1       dog      pitbull
2       dog      Shetland sheepdog
3       dog      Boxer
4       cat      Dragon Li
5       cat      Australian Mist
6       cat      Korat

In the c# designer view, I have 2 drop-down list one which has species and other for breed.

What I want is that when user picks 'dog' in species list, the breed list should have the following Alsatian, pitbull, Shetland sheepdog,Boxer

At the moment when I pick 'dog', all the breed from the database is shown.

<asp:DropDownList ID="DropDownListSpecies" runat="server" 
     Height="27px" Width="107px" DataSourceID="hs330" 
     DataTextField="Species" DataValueField="Species">
</asp:DropDownList>
<asp:SqlDataSource ID="Species" runat="server" 
     ConnectionString="<%$ ConnectionStrings:ConnectionString %>" 
     SelectCommand="SELECT DISTINCT [Species] FROM [Breed]">
</asp:SqlDataSource>

<asp:DropDownList ID="DropDownListBreed" runat="server" Height="20px" 
    Width="110px" DataSourceID="breed" DataTextField="Breed" 
    DataValueField="Breed">
</asp:DropDownList>
<asp:SqlDataSource ID="breed" runat="server" 
    ConnectionString="<%$ ConnectionStrings:ConnectionString %>" 
    SelectCommand="SELECT DISTINCT [Breed] FROM [Breed]">
</asp:SqlDataSource>

解决方案

You need to use ControlParameter in SelectParameters.

Make sure that AutoPostBack="True" for DropDownListSpecies

FYI: You have typo in Speecies

<asp:DropDownList ID="DropDownListSpecies" runat="server"
    Height="27px" Width="107px" DataSourceID="Species"
    DataTextField="Species" DataValueField="Species" AutoPostBack="True">
</asp:DropDownList>
<asp:SqlDataSource ID="Species" runat="server"
    ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
    SelectCommand="SELECT DISTINCT [Species] FROM [Breed]"></asp:SqlDataSource>
<asp:DropDownList ID="DropDownListBreed" runat="server"
    Height="20px" Width="110px"
    DataSourceID="breed" DataTextField="Breed" DataValueField="Breed">
</asp:DropDownList>
<asp:SqlDataSource ID="breed" runat="server"
    ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
    SelectCommand="SELECT DISTINCT [Breed] FROM [Breed] WHERE Species=@Species">
    <SelectParameters>
        <asp:ControlParameter ControlID="DropDownListSpecies" PropertyName="SelectedValue"
            Name="Species " Type="String" DefaultValue="cat" />
    </SelectParameters>
</asp:SqlDataSource>

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