How can a SqlDataSource include dynamic inputs? (Ex: Sql Statements, ConnectionString, Etc.)

Here is a sample of what I am looking to acheive (This is the code in question):

<asp:SqlDataSource id="DataSource" Runat="Server" ProviderName="System.Data.SqlClient"
  ConnectionString="Your Connection String Here"
  SelectCommand="SELECT ProductName FROM DatabaseTable WHERE ProductId = '%' + Container.ProductId + '%' "/>
</asp:SqlDataSource>

I am able to pass other values through the aspx page using code like: 
<%# Container.ProductId %>
<%# Container.CategoryName %>
<%# Localization.GetString("Button.Text", LocalResourceFile) %>

Since <%# Container.ProductId %> already is passing values, how can I include this same source within the SqlDataSource?

Feedback Appreciated.

 

I am familiar with using these methods, although in this instance I am modifying a .ascx file that has <%@ control %> declaration rather than a <%@ page %> declaration.

The current .ascx file doesn't reference a codeBehind or codeFile value: 
<%@ control language="C#" autoeventwireup="true" inherits="NameofInheritance" %>

When I add "CodeBehind="filename.ascx.cs"" it doesn't seem to be listening to the .cs codebehind file.
When I add "CodeFile="filename.asxc.cs"" the module throws errors.
 

1.  What am I missing to have the .ascx successfully reference an external .cs codebehind?

2.  Can't this also be acheived within <script> of the .ascx file? 
     When testing within <script> I am not getting a response either.
     <script type="c#/text" language="C#" runat="server">
           labeltest.text = "Testing";
     </script>

Feedback Appreciated.

The inheritance which is already determined must be the problem, while the source files are compiled into a .dll file.  Since there cannot be 2 <%@ control %> declarations on the same page, how can I reference an additional external codebehind?  Shouldn't <script> within .ascx file work as well?  Is there a way to embedd a .ascx value into SqlDataSource Select Command (initial post)? 

Feedback Appreciated.