In brief, within the Netbeans editor the autocompletion feature uses pattern that user types from the beginning letter by letter. In case the user forgets the exact beginning of the command he wants to type, the editor won't suggest anything.
In opposition to this behavior some editors (like Atom, Brackets, etc) show suggestions regardless of the position of the pattern in the statement which one types. Say if I type "report" I'll see suggestions like "mysqli_report..", "error_reporting..", etc.; in case of Netbeans I will see nothing useful.
To sum up, I think it could be a good idea to add this feature in Netbeans as well.

Please see the original topic: http://forums.netbeans.org/viewtopic.php?p=172666#172666