PHP Composer Autoloader Class not Found Exception
You need to include namespace when you are initializing a class:
$mysql = new Database\Core\MySQL();or
use Database\Core\MySQL;$mysql = new MySQL();
Aside from not using the right use statement as already mentioned, PSR-4 does not work like that. It is more of an alias. You are essentially saying that src equals Database. So to have a directory named Database in there would imply that the fully qualified namespace + class equals 'Database\Database\Core\MySQL`. You want to use PSR-0 in this case, or adjust your PSR-4 definition.