[New API] Change a Players' Gamemode

Just a quick question, but how do i change a players gamemode when they enter a certain world? Trying to create a plugin for this.

PHP:

$player->setGamemode(0); //Set
$player->getGamemode(); //Get

Ok thanks.

Make sure to save their inventories before switching them!

how

If you ever finish this plugin i would love to use it foe my server if its ok with you.

Make a database of yourself. Remember not to use a single YAML file to save inventories

making too many queries would sometimes makes the mysql server respond slow and needs a restart on certain interval.

Who told you to use a MySQL server? And even if you do, who told you to make many queries?