session_destroy — Destroys all data registered to a session
session_unset — Free all session variables
unset - unset a variable
unset() 和session_destroy()的区别如下:
Unset will destroy a particular session variable whereas session_destroy() will destroy all the session data for that user.
It really depends on your application as to which one you should use. Just keep the above in mind.
unset(¥_SESSION['name']); // will delete just the name data
session_destroy(); // will delete ALL data associated with that user.