<p>This is my add form:<br>&lt;AddForm&gt;</p><p> &lt;ScriptBlock BlockType="HeadScript" RegisterOnce="True" ScriptId="XMODPro_Admin"&gt;</p><p> &lt;link rel="stylesheet" type="text/css" href="/DesktopModules/XModPro/styles/rcde-admin/styles.css" /&gt;</p><p> &lt;/ScriptBlock&gt;</p><p> &lt;SubmitCommand CommandText="INSERT INTO [RCDEProduct_Categry] (ProductId,CategoryId) VALUES(1,1)" /&gt;</p><p> &lt;ControlDataSource Id="CategoriesDataSource"</p><p> CommandText="</p><p> SELECT </p><p> CONVERT(VARCHAR,ISNULL(ParentCategoryId,-1))+'|'+CONVERT(VARCHAR,Id) AS [Id]</p><p> ,'['+ CONVERT(VARCHAR,[CategoryNumber]) + '] '+[Name] AS [Name]</p><p> FROM </p><p> [RCDECategory] </p><p> WHERE</p><p> ParentCategoryId IS NOT NULL</p><p> ORDER BY </p><p> ParentCategoryId,</p><p> [Name] ASC"</p><p> /&gt;</p><p> &lt;ControlDataSource Id="RootCategoriesDataSource"</p><p> CommandText="</p><p> SELECT </p><p> [Id]</p><p> ,'['+ CONVERT(VARCHAR,[CategoryNumber]) + '] '+[Name] AS [Name]</p><p> FROM </p><p> [RCDECategory] </p><p> WHERE</p><p> ParentCategoryId IS NULL</p><p> ORDER BY </p><p> [Name] ASC"</p><p> /&gt;</p><p> &lt;div&gt;</p><p> &lt;div&gt;</p><p> &lt;h3&gt;New Category Assignment for: [[Form:Id]]&lt;/h3&gt;</p><p> &lt;/div&gt;</p><p> &lt;div&gt;</p><p> &lt;ListBox id="CategoriesListBox" cssclass="collapse"</p><p> DataSourceID="CategoriesDataSource" DataTextField="Name" DataValueField="Id" /&gt;</p><p> &lt;ValidationSummary CssClass="alert alert-danger" Id="ValidationSummary" DisplayMode="List" HeaderText="Please check your entries:"&gt;&lt;/ValidationSummary&gt;</p><p> &lt;div&gt;</p><p> &lt;Label For="Category"&gt;Category&lt;/Label&gt;</p><p> &lt;DropDownList id="Category" cssclass="form-control"</p><p> DataSourceId="RootCategoriesDataSource" DataValueField="Id" DataTextField="Name" DataType="int32"</p><p> Nullable="False" /&gt;</p><p> &lt;Validate Target="Category" cssclass="text-danger"</p><p> Type="required" Text="- Must select a Category." Message="- Must select a Category." /&gt;</p><p> &lt;/div&gt;</p><p> &lt;div&gt;</p><p> &lt;Label For="Subcategory"&gt;Subcategory&lt;/Label&gt;</p><p> &lt;DropDownList id="Subcategory" cssclass="form-control"</p><p> DataType="int32" Nullable="True" /&gt;</p><p> &lt;/div&gt;</p><p> &lt;/div&gt;</p><p> &lt;div&gt;</p><p> &lt;AddButton Text="Add" cssclass="btn btn-primary"&gt;&lt;/AddButton&gt;</p><p> &lt;CancelButton Text="Cancel" cssclass="btn btn-default" Visible="true"&gt;&lt;/CancelButton&gt;</p><p> &lt;/div&gt;</p><p> &lt;/div&gt;</p><p> &lt;jQueryReady&gt;</p><p> //+- Initialize Variabes</p><p> var $rootCategories = $('[name$="CategoriesListBox"]');</p><p> //+- Define Event Handlers</p><p> $('body')</p><p> .on('change','select[name$="Category"]',CategoryChange);</p><p> //+- Trigger Evens</p><p> $('select[name$="Category"]').change();</p><p> //+- Event Handlers</p><p> function CategoryChange(){</p><p> var selectedCategory = $(this).val();</p><p> var $options = $rootCategories.find('option[value^="' + selectedCategory + '|"]').clone();</p><p> $options.each(function(){</p><p> var val = $(this).val();</p><p> var categoryId = val.split("|")[1];</p><p> $(this).val(categoryId);</p><p> });</p><p> $('[name$="Subcategory"] option').remove();</p><p> $('[name$="Subcategory"]').append($options);</p><p> $('[name$="Subcategory"]').closest('.form-group').show();</p><p> if($('[name$="Subcategory"] option').length==0){</p><p> $('[name$="Subcategory"]').closest('.form-group').hide();</p><p> }</p><p> }</p><p> &lt;/jQueryReady&gt;</p><p>&lt;/AddForm&gt;</p>