php dot和mysql dot不匹配

Hi I have a table that looks like this:

|   vend   |   prod_name   |   price   |   qty   |
|----------|---------------|-----------|---------|
|   vend1  |   red wine    |   15.00   |    3    |
|----------|---------------|-----------|---------|
|   vend1  |  nike tg. 42  |   70.00   |    10   |
|----------|---------------|-----------|---------|

the problem with the code below is that when I update qty for red wine all works fine, but when I do the same thing with nike tg. 42 the update doesn't work. I think that the problem is that dot that I can't remove. The default charset of the database is latin1 and collate is latin1_general_cs.

 $connection = mysqli_connect($host, $DBuser, $Dbpass, $databaseName);
 $query = 'update prodotti set qty = ? where vend = ? and prod_name = ?';
 $st = mysqli_prepare($connection, $query);
 mysqli_stmt_bind_param($st, 'iss', $value, $_SESSION['NomeUtente'], $key);
 mysqli_stmt_execute($st);
 mysqli_stmt_close($st);

Note that I've already print $key variable and it is exactly nike tg. 42

use a query like this

update prodotti set qty = '11' where vend = 'vend1' and prod_name = 'nike tg. 42';

i only want to show to use that value you obtained in a single quote the above query i had given worked fine for me i think mysqli_stmt_bind_param() causing error bcos u are not able to get single quotes with it try with direct query and get value in itself try and reply if any error