Use the HtmlSelect.DataSourceID property to set or access the System.Web.UI.Control.ID property of the data source control that the System.Web.UI.HtmlControls.HtmlSelect control should use to retrieve its data source. The data source control referenced by the HtmlSelect.DataSourceID property can be any control that implements the System.Web.UI.IDataSource interface. The data source control must exist either in the same naming container as the System.Web.UI.HtmlControls.HtmlSelect control that references it or in a parent control of the System.Web.UI.HtmlControls.HtmlSelect control. When you specify a value for this property, the System.Web.UI.HtmlControls.HtmlSelect control automatically binds to the specified data source control. You do not need to write code that explicitly calls the System.Web.UI.Control.DataBind method.

Alternately, you can use the HtmlSelect.DataSource property to specify the source of values to bind to an System.Web.UI.HtmlControls.HtmlSelect control. The data source must be a collection that implements the IEnumerable interface (such as System.Data.DataView, ArrayList, or List`1) or the System.ComponentModel.IListSource interface. When you set the HtmlSelect.DataSource property, you must manually write the code to perform data binding.

If values are specified for both the HtmlSelect.DataSource property and the HtmlSelect.DataSourceID property, ASP.NET is not able to resolve the data source and a System.Web.HttpException exception is thrown.