AJAX

AJAX in Action: very good book that describes AJAX technologie and gives a lot of real life code.

Databases

I asked on fr.comp.applications.sgbd French Usenet group recommandations for a good book on SQL.
- The prefered book SQL - La réference ! is out of print;
- web site http://sql.developpez.com/ gives a lot of articles on SQL;
- Book Apprendre SQL avec MySQL is recommended by web site http://sgbd.developpez.com/livres/