SELECT abcd FROM `goods` AS g WHERE is_delete = 0 AND is_alone_sale = 1 AND ( 1 AND cat_id IN ('8','') AND (0 OR goods_name LIKE '%高级商务%' OR goods_sn LIKE '%高级商务%' OR keywords LIKE '%高级商务%' ) ) OR goods_id IN ('') ORDER BY goods_id DESC

上面的这条查询语句运行无错，我现在去掉AND (1中的1，这样运行后打印出如下SQL语句：
SELECT abcd FROM `goods` AS g WHERE is_delete = 0 AND is_alone_sale = 1 AND ( AND cat_id IN ('8','') AND (0 OR goods_name LIKE '%高级商务%' OR goods_sn LIKE '%高级商务%' OR keywords LIKE '%高级商务%' ) ) OR goods_id IN ('') ORDER BY goods_id DESC

请看AND ( 这儿，这儿比原来的少了1，但运行出错了，提示如下：
Fatal error: Call to a member function on a non-object in search.php on line 278

想不通去掉了这个1运行就无效了，这里的1是不是is_delete = 0 AND is_alone_sale = 1这两个表达式的结果值？如果我的理解不对，请大家纠正一下。

还有，AND (0这儿，这里的0也是哪个表达式的结果值吗？如果不是，那代表什么意思？

以上是逻辑运算方面的，我对照手册看了半天还是无法理解，恳请得到大家的帮助，谢谢。