protected void GridView1_SelectedIndexChanging(object sender, GridViewSelectEventArgs e)
    {
        string Id = GridView1.DataKeys[e.NewSelectedIndex].Value.ToString();  //错误
      
       
        string SqlStr = "select * from bbs where u_id='" + Id + "'";
        DBLink db = new DBLink();       
        GridView2.DataSource = db.SelectSqlReturnDataSet(SqlStr);
        GridView2.DataBind();
        
    }