Geeks of the World, Unite!

Four young friends (Blaise, Charles, John, and Konrad), who met at a LAN party, have recently taken jobs at the same technology services firm. All of them work in the web development division and they were all hired as junior programmers because of their inexperience. They all work with different languages (AJAX, Perl, PHP, and Ruby on Rails (RoR)), different information systems (JSON, MySQL, plain text, and XML), and have been using those languages and systems a differing amount of time (3 months, 5 months, 6 months, 9 months).

Using the clues provided, can you figure out who has been using what language with what system for what amount of time?

1. MySQL has been used longer than RoR.
2. The four friends are John, the one who uses PHP, the one who has been at it for 9 months, and the one who uses plain text.
3. Blaise is happy he doesn't have to work with Perl.
4. Plain text has been used longer than PHP, but not as long as AJAX.
5. One of the languages start with the same letter as its corresponding system.
6. Charles has been working with his language and system longer than John, but not as long as the person who uses AJAX.
7. The four information systems are XML, the one used with PHP, the one that's been used for 6 months, and the one that Konrad uses.
8. JSON has not been used the most amount of time and XML hasn't been used the least amount of time.
9. The four languages used are AJAX, the one used for 5 months, the used by Charles, and the one used with JSON.