Programming Buddies,

Looking at the following links, can you be kind enough to tell me which one I should learn from and which one teaches what method (mysqli, pdo, etc.) and whether they are on php 7 or 5 because only looking for php 7:

And, is this a good way to prevent sql injection ? It is unorthodox, I guess:

And, at what point do you recommend I learn about PDO and do you recommend them which a programmer recommended: