查询表名为tb_menu的所有列名

select name from syscolumns where id=object_id('tb_menu') 

查询表名为tb_menu的所有列名个数

select count(name) from syscolumns where id=object_id('tb_menu') 

或者

select count(syscolumns.name)
from   syscolumns ,sysobjects    
where  syscolumns.id=sysobjects.id  and sysobjects.name = 'tb_menu'