Untitled

Access HttpContext.Current.User.Identity.Name as Parameter to SqlDataSource
<SelectParameters>
            <asp:ControlParameter ControlID="SelectLoadScanner1" DefaultValue="0" Name="loadId" PropertyName="loadId" />
            <asp:SomeParameterType DefaultValue="" Name="username" PropertyName="HttpContext.Current.User.Identity.Name" />
        </SelectParameters>

public string UserName
{
    get
    {
        if (HttpContext.Current == null || HttpContext.Current.User == null)
            return null;
        else
            return HttpContext.Current.User.Identity.Name;
    }
}