you should export your mysql database (or certain parts of it), and copy it into a new database.
Thats useless for this purpose. There is post ID # collision, category merging to deal with and so on. A whole host of issues that would need to be considered. A simple SQL based merge process is doomed to fail.
Yes, this buggers me too. I see on the Codex that among WP 1.6’s new features there’s Lossless XML import/export, which could address this issue. But I seem to remember this already being in the list for 1.5, back in the days, so…
Frankly, there’s no reason not to have this in WP. Event MT did it right (no flames, please), back in their 2.x days. The whole point of being able to export all your data from WP (and reimporting them again) is that it is your data and you care about it!
Now, I know there are solutions for backing up your data directly from MySQL, or through a plugin or another. But such a feature directly built into WP would make it even easier for the mythical “average user”: my mum couldn’t care less about MySQL and phpMyAdmin, but she sure would care about what she wrote on her WP-site. She couldn’t care less about the format of import/export, be it a bunch of text files or XML, but she could see immediately “Ah, here I can backup all of last year’s writing, save it to CD, and if I mess everything up I will be back with my content on-line in no time”.
WP developers have astonished and surprised me in many good ways since a couple of years now. Such an import/export feature really would be another top feather in their hats, and I hope they’re thinking about it.
I spent some time looking into the problem, and if push comes to shove I will write a tool to do it but frankly I am not really going to spend the time to try and make it “universal”. It will just be some PHP that needs to be able to connect to both the old and the new DB’s and then it will handle the merge issues.
Of course, depending on when 1.6 is due I might just wait till it shows up, upgrade both installations and see if that is useful.
Still, the lack of this basic feature is simply astonishing. Don’t get me wrong, I appreciate all the work the core team has done… but it still baffles me 🙂
Ok, I have to ask…
Has anyone ever done this at all? Merge 2 WP blogs? Even with the now broken plugins?
Beuller?
Just an update. A few hours hacking and I have a WP -> XML tool running. It puts out the essential post data, categories and authors. I haven’t done comments yet.
Obviously the import / merge is where the magic happens, but so far this is working OK.
I created a blog on my laptop, and may continue to do so. My need was to write over the new blog installed on my desktop. After about an hour of trying things, I got a procedure that works.
It uses phpMyAdmin to export SQL files. Use complete inserts, save as file, replace, and if-not-exists. You may have to use an editor with global search and replace to kill fields if you’re porting mis-matched WordPress versions. I had to kill a bunch of latitude and longitude fields in the exported SQL file. Then use mysql to import the file. Use the source command.
Port 3 tables – categories, post2cat, and posts. If you’ve dabbled with these tools, that may be enough. If not, pop me an email and I may have a nice pdf instruction document by then — or shoot, I may have it in my new blog by then 🙂
Again a reminder, this just writes over existing data. That’s okay with me since I created a virgin database on my new computer to take the old database info.
BTW, to the developers that are smarter than me: “It would be really nice to have a WP -> WP export and import capability.”
This is very important to users like me, who start out with several test blogs that eventually grow into serious blogs. Now I need to merge them, but I can’t. I’d contribute to a bounty for this kind of feature.
