public AjaxControlToolkit.CascadingDropDownNameValue[] GetOrdersByEmployeeID(string knownCategoryValues, string category)
{

//字符串字典 這個(gè)類 么用過 看別人是這么寫的
//也可以這么用：string [] strValues=knownCategoryValues.Split(':',';');
// 然后取值： strValues[0]是 name strValues[1]是value吧

System.Collections.Specialized.StringDictionary kv = CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
int iEmployee;

//其中Employee就是父控件傳入的knownCategoryValues參數(shù)中傳過來的一個(gè)類別，父控件的Category的值是"Employee"
//knownCategoryValues的值是則是："EmployeeName:value;" 類型
//如果父控件中[WebMethod]方法中是如下加入的值
// list.Add(new AjaxControlToolkit.CascadingDropDownNameValue("張三","123"));
//則knownCategoryValues中是 "Employee張三:123;" (如果這里有誤,請(qǐng)大蝦們指導(dǎo)下)
//方法中的category則是Category的值,這里下蝦我迷惑的是,這個(gè)值是本控件的Category的值還是父控件的值?
//我認(rèn)為是調(diào)用此方法的category的CascadingDropDown的Category的屬性,原因是父控件的這個(gè)屬性是在knownCategoryValues值中判斷出來的

if (!kv.ContainsKey("Employee") || !Int32.TryParse(kv["Employee"], out iEmployee))
{
return null;
}
//下面的取數(shù)據(jù)方法可以根據(jù)項(xiàng)目中的實(shí)際情況更改,這里我用的是一個(gè)大蝦博客上的一個(gè)方法做示例,因?yàn)樽约簩懙男枰趕ql語句中添加一些判斷,并且數(shù)據(jù)表表陌生,
string stringConnection = "Server=.;DataBase=Northwind;uid=sa;pwd=sl";
System.Data.SqlClient.SqlConnection conn= new System.Data.SqlClient.SqlConnection(stringConnection);
System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand("SELECT OrderID FROM Orders WHERE EmployeeID = " + iEmployee);
cmd.Connection = conn;
System.Data.SqlClient.SqlDataAdapter da = new System.Data.SqlClient.SqlDataAdapter(cmd);
System.Data.DataSet ds = new System.Data.DataSet();
da.Fill(ds);
cmd.Connection.Close();
//
System.Collections.Generic.List<AjaxControlToolkit.CascadingDropDownNameValue> list = new System.Collections.Generic.List<CascadingDropDownNameValue>();

//下拉列表中的值
foreach (System.Data.DataRow dr in ds.Tables[0].Rows)
{
string sOrder=dr["OrderID"].ToString();
int iOrder=(int)dr["OrderID"];
//CascadingDropDownNameValue("Name","Value") name是在DropDownList中顯示的text value是DropDownList的 value
// DropDownList中的selectedValue則傳給下個(gè)控制dropdownList的CascadingDropDown調(diào)用的webService方法中的knownCategoryValues的值

list.Add(new AjaxControlToolkit.CascadingDropDownNameValue(sOrder,iOrder.ToString()));
}
return list.ToArray();
}

<asp:DropDownList ID="DropDownList1" runat="server">
</asp:DropDownList>
<asp:DropDownList ID="DropDownList2" runat="server">
</asp:DropDownList>
<asp:DropDownList ID="DropDownList3" runat="server">
</asp:DropDownList><br />
<cc1:CascadingDropDown ID="CascadingDropDown1" runat="server" Category="Employee" Enabled="True" PromptText="Select Employee" ServiceMethod="GetEmployees" TargetControlID="DropDownList1" ServicePath="AutoComplete.asmx">
</cc1:CascadingDropDown>
<cc1:CascadingDropDown ID="CascadingDropDown2" runat="server" ParentControlID="DropDownList1" Category="Order" Enabled="True" PromptText="Select Order" ServiceMethod="GetOrdersByEmployeeID" TargetControlID="DropDownList2" ServicePath="AutoComplete.asmx">
</cc1:CascadingDropDown>
<cc1:CascadingDropDown ID="CascadingDropDown3" runat="server" ParentControlID="DropDownList2" Enabled="True" PromptText="Select Pice" ServiceMethod="GetDetailsByOrder" TargetControlID="DropDownList3" ServicePath="AutoComplete.asmx" Category="Pice">
</cc1:CascadingDropDown>