Best way to connect to MySQL with PHP securely [duplicate]

Answer 1

• Define a pair of proper login credentials instead of "root/root" (change the user name to something else, and choose a complicated password);

• if possible restrict access to the database to localhost on a firewall level or, as @Scott says in the comments, set mySQL to listen to connections from 127.0.0.1 only. If both is not possible, restrict access on mySQL level. ("username"@"localhost")