ObjectContext 实例已释放，不可再用于需要连接的操作。
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
LoadUserDropDownList();
}
}
3.Page_Load方法中的LoadUserDropDownList方法代码如下：
private void LoadUserDropDownList()
{
using (OrderDBContainer db = new OrderDBContainer())
{
ddlUsers.DataSource = from u in db.UserAccounts
orderby u.LastName
select new { Name = u.LastName + ", " + u.FirstName, Id = u.Id };

ddlUsers.DataTextField = "Name";
ddlUsers.DataValueField = "Id";
ddlUsers.DataBind();//////////////ObjectContext 实例已释放，不可再用于需要连接的操作。

ddlUsers.Items.Insert(0, new ListItem("Create New User", ""));
}
}
当运行到DataBind()时候就出现如题
我想了一个晚上，想不明白，这为什么？是不是VS2010中文版BUG
使用Entity Framework例子

[解决办法]
ddlUsers.DataSource = from u in db.UserAccounts
orderby u.LastName
select new { Name = u.LastName + ", " + u.FirstName, Id = u.Id };

=>

ddlUsers.DataSource = (from u in db.UserAccounts
orderby u.LastName
select new { Name = u.LastName + ", " + u.FirstName, Id = u.Id }).ToList();