Access to wordpress method inside of classes

get_current_site() is a (globally accessible) function (located in ms-functions.php), it’s not a class method, so simply call it it by its name like you would do with any other function.

$currentSite = get_current_site();

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)