Gridview in C# dont show data and a big eror :  i am trying to show my data table with a grid view 

     protected void show_data(object sender, EventArgs e)
        {
            string str = "Data Source=(LocalDB)\\MSSQLLocalDB;";
            str += "AttachDbFilename=|DataDirectory|DinoData.mdf;";
            str += "Integrated Security= True";
            SqlConnection c;
            c = new SqlConnection(str);
            GV.DataSource = User;
            GV.DataBind();
        }

the eror:

> An exception of type 'System.InvalidOperationException' occurred in
> System.Web.dll but was not handled in user code
> 
> Additional information: Data source is an invalid type.  It must be
> either an IListSource, IEnumerable, or IDataSource.

what should i do?
and if i want to show only part of the table with gridview how to do it?
thanks for helping