I would like to learn the use of prepared sentences and have I got these pages online, will they be updated? , because I've seen some use MYSQL
The guides are reasonably updated, and the latest is the official documentation of PHP, so it is the most up-to-date information that can exist about it.
Regarding your question about the use of MySQL, I commented that MySQL is a database engine. From PHP you can connect to this engine using extensions mysql , mysqli and PDO-MySQL Of these three, the first one is abandoned, obsolete, deprecated and disregarded, but it is not the same to give for dead the extension mysql in particular that the connectors to the MySQL engine as a whole.