不要在表名周围使用单引号，而是使用反引号 (`):

Don't use single quotes around your table name, use backticks (`) instead:

$query = mysql_query("SELECT * FROM `$category` WHERE title LIKE '%$search_title%'");

注意.请确保 $category 和 $search_title 不是普通的用户提供的变量

NB. Please make sure that $category and $search_title are not plain user provided variables