is it possible to upgrade from 1.0 to 1.2.1, wihout upgrade to 1.1->1.2?

our side is 1.0 and I want to upgrade it to the new version.

Basically, what you want to do is follow each of the individual update instructions (using the 1.2.1 files), but only run the actual update script at the very end with the instructions for 1.2 -> 1.2.1.

As long as you make the file and other changes as indicated, then the update script will step you through each necessary update; first from 1.0 to 1.1, then 1.1 to 1.2, and finally 1.2 to 1.2.1.

(Remember, make a site/database backup before doing any update.)

the problem I don’t have 1.1 and 1.2 source code to run the update script for each version. could I can get them from website? I can only download the latest one

oops, I have found that I have the source code 1.1, but 1.2 I have lost because of harddisk damage!

As I mentioned in my first message, you don’t need those versions of the file.  Whenever it talks about copying/replacing files just use the 1.2.1 versions.