Database update

Hi all, I have installed the new XWiki version. In fact, I used an old version and try to update with the new one (xwiki-0.9.1252). But, I found that the new database is a script file stored in ../db directory! And check before the the MySQL databases but not find any xwiki database, even I have removed the MySQL installation but the xwiki work!! What's kind of database is used in the new XWiki version? And how updating it from the old MySQL database. Many thanks in advance. Youcef