select t1.* from bbs_product as t1, bbs_category as t2 where (((t1.product_name_de like '%13"%') or (t1.sku_number like '%13"%') or (t1.description like '%13"%')) and ((t1.product_name_de like '%Laptoptasche%') or (t1.sku_number like '%Laptoptasche%') or (t1.description like '%Laptoptasche%')) and ((t1.product_name_de like '%im%') or (t1.sku_number like '%im%') or (t1.description like '%im%')) and ((t1.product_name_de like '%Buchdesign%') or (t1.sku_number like '%Buchdesign%') or (t1.description like '%Buchdesign%'))) and (t1.category_id=t2.id and t2.status=1) and t1.status=1 and t1.discontinued='no' and t1.is_secret='n'
t1.sku_number like '%13"%') or (t1.description like '%13"%')) and
В тексте запроса есть двойные кавычки.
Убедитесь, что они правильно экранированы в строке PHP, которая является аргументом mysql_query.
PHP
mysql_query