如果我硬编码数据库中的文本，mysql查询将只返回结果

I have a MYSQL database with a query. The query only works if I manually type in the data with MYSQL Admin or with the following statement $sn="x-xxx"; It will not return results if i pass $sn to the database from a form even though the $sn get inserted into the database just fine. I can look at the database and see that it's there. Not sure if why the query would only pull down the records I manually imputed. I have a MYSQL database with a query. The query