How to remove bad characters that are not suitable for utf8 encoding in MySQL?

Question

I have dirty data. Sometimes it contains characters like this. I use this data to make queries like

WHERE a.address IN (\'mydatahere\')

For

Answer 1

In PHP - I approach this by only allowing printable data. This really helps in cleaning the data for DB.
It's pre-processing though and sometimes you don't have that luxury.

$str = preg_replace('/[[:^print:]]/', '', $str);