mediawiki upgrade

Hi everyone,

I'd like to upgrade from 1.3.1 to 1.3.9 on our internal network.
First I backup the database :
mysqldump -u root -p wikidb > wiki.db

Then, I follow the normal setup of a fresh install of mediawiki 1.3.9

When I want to restore my old data :
cat wiki.db | mysql -u root -p wikidb
this tells me : "ERROR 1050 at line 11: Table 'archive' already exists"

Indeed, the definition of the table 'archive' seems to be at line 11 of 
file wiki.db, and I guess that the fresh install of mediawiki already 
created such a table.

So my question would be : how do i get my old data back into my new 
install of mediawiki ?

Thank's for any help.

I've been looking through the pages :
http://meta.wikimedia.org/wiki/How_to_become_a_MediaWiki_hacker
http://fr.wikipedia.org/wiki/Wikip%C3%A9dia:Installation_du_logiciel
.... but i could not get any information on this problem.