MySQL保持返回一行，即使数据库中没有任何内容与查询匹配

$query_check_homework keeps failing even though there is nothing in the database. I am sure this is probably something really simple like a syntax error but I have been working at this for over an hour and cannot get it working. Could you please take a look at the code and let me know why it keeps returning a row even though nothing is in the database that matches the query.$query_check_homework keeps failing even though