create a new DB user for your client, give them acces to READ your database only.
Then any INSERT UPDATE and DELETE commands will be ignored.
In addition, including your config php from a remote site, as it uses "localhost" for the hostname, will not work, you'll need to get the DNS/IP address for your SQL server and use that. In addition some hosts only allow connections to the database from inside their datacenters, so they maynot beable to connect like that.
In that case, you'll need to create some sort of gateway.