myeclipse 关于排序问题

制作出一个借阅书最多的系的排名

String sql="select top 10 t2.bookName,sum(t1.number) as num"+  
" from tb_order_detail t1,tb_book t2,tb_order t3"+  
" where t1.bookID=t2.ID "+ 
" group by t2.bookName "+ 
" order by num desc";
String sql1="SELECT COUNT(dept) AS num1 "+
" from dbo.tb_order"+ 
" group by dept";

ResultSet rs = conn.executeQuery(sql);
String bookName = "";
String dept="";
int num = 0;
int num1 = 0;

报错内容是dept列名无效，以及已经在数据库的tb_order中加入了dept新列，并在其他页面运用成功。

报错信息发出来看看