public void Category()          {             var result = from r in lqDB.Category                          select new                         {                              r.Category1,                              r.CategoryID                          };             CID.DataSource = result;             CID.DataBind();         }         public void Varietes()          {              int id = Int32.Parse(CID.SelectedValue);             var result = from r in lqDB.Varieties                                                     select new                          {                                    r.Varieties1,                             r.VarietiesID,                             r.VCID                          };             VS.DataSource = result;             VS.DataBind();         }

这是后台代码

 <asp:DropDownList ID="CID" runat="server" DataTextField="Category1" DataValueField="CategoryID" AutoPostBack="True"  >             <asp:ListItem>VCID</asp:ListItem>         </asp:DropDownList>         <asp:DropDownList ID="VS" runat="server" DataTextField="Varieties1" DataValueField="VarietiesID" AutoPostBack="True">         </asp:DropDownList>

这是前台
我准备实现的是下拉框级联
数据库

 CREATE TABLE [dbo].[Category] (     [CategoryID] INT           IDENTITY (1, 1) NOT NULL,     [Category]   NVARCHAR (50) NULL,     CONSTRAINT [PK_Category] PRIMARY KEY CLUSTERED ([CategoryID] ASC) ); CREATE TABLE [dbo].[Varieties] (     [VarietiesID] INT           IDENTITY (1, 1) NOT NULL,     [Varieties]   NVARCHAR (50) NULL,     [VCID]        INT           NULL,     CONSTRAINT [PK_Varieties] PRIMARY KEY CLUSTERED ([VarietiesID] ASC),     CONSTRAINT [FK_Varieties_Category] FOREIGN KEY ([VCID]) REFERENCES [dbo].[Category] ([CategoryID]) );
 CREATE TABLE [dbo].[KC] (     [ID]            INT           IDENTITY (1, 1) NOT NULL,     [CategoryID]    INT           NULL,     [VarietiesID]   INT           NULL,     [Type]          NVARCHAR (50) NULL,     [ColorID]       INT           NULL,     [LayerID]       INT           NULL,     [ThicknessID]   INT           NULL,     [Specification] NVARCHAR (50) NULL,     [Meter]         NVARCHAR (50) NULL,     [Square]        NVARCHAR (50) NULL,     [Data]          NVARCHAR (50) NULL,     [Number]        INT           NULL,     [Remark]        NVARCHAR (50) NULL,     [Nmb]           NCHAR (10)    NULL,     CONSTRAINT [PK_KC] PRIMARY KEY CLUSTERED ([ID] ASC),     CONSTRAINT [FK_KC_Layer] FOREIGN KEY ([LayerID]) REFERENCES [dbo].[Layer] ([LayerID]),     CONSTRAINT [FK_KC_Category] FOREIGN KEY ([CategoryID]) REFERENCES [dbo].[Category] ([CategoryID]),     CONSTRAINT [FK_KC_Varieties] FOREIGN KEY ([VarietiesID]) REFERENCES [dbo].[Varieties] ([VarietiesID]),     CONSTRAINT [FK_KC_Color] FOREIGN KEY ([ColorID]) REFERENCES [dbo].[Color] ([ColorID]),     CONSTRAINT [FK_KC_Thickness] FOREIGN KEY ([ThicknessID]) REFERENCES [dbo].[Thickness] ([ThicknessID]) );

下拉框级联怎么刷新不了？
我集合写了啊.
求代码

选择的时候下拉框不能实现级联啊.我那里有问题，
麻烦各位帮在下修改一下代码
 <span style="color: #FF0000;">where r.ID = id</span>
把那些绑定全部放到非回传判断里  否则 你的dropdownlist启用了自动回传  那你的数据源都会重新加载！！