mySQL数据库报错You have an error in your SQL syntax

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'order by cid desc' at line 1
这是一个什么错误啊，请大侠指点
SQL Error:
MySQL Query Error
select * from dg_taobao_cat where cid= order by cid desc
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'order by cid desc' at line 1
PHP Backtrace
File Line Function
includesdb_mysql.class.php 92 db_mysql->halt()
includestable.class.php 119 db_mysql->query()
taobao.php 79 TableClass->getdata()
taobaoview.php 144 taobao_position()
taobao.php 42 include_once()