I used the new mysqli syntax because with the mysql version I had errors on local BD and other BD.
However, when I use mysqli, I have NO errors in local BD, but got errors in the other BD:
Warning: mysqli_connect(): The server requested authentication method unknown to the client [mysql_old_password], Warning: mysqli_query() expects parameter 1 to be mysqli, boolean given, Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, null given.
Yup, I have these errors when connected to the OTHER BD, though I use mysqli.
If it has some importance, the local BD has no password(and user is ROOT), the other BD HAS password.