Sometimes more than one WordPress installation is necessary on a single site and WPMU would be overkill, or sometimes a hosting provider limits the number of available databases per account, or maybe you just want to keep things more organized rather than have a bunch of databases scattered everywhere. In any case, you’ll want to install multiple instances of WordPress, each one using the same database.
Luckily, this is quite simple to do, but you must install WordPress manually in order for it to work properly. A majority of the one click installations (most common is Fantastico) do not allow you to specify the prefix to use and this is absolutely necessary to be met with success.
During the installation process*, when it comes time to modify your wp-config.php file (or on the WordPress config options screen), make sure that you change the default wp_ prefix to something different.
I prefer using an identifier for the specific blog that WordPress is being installed on. For instance, if I were installing it for the OptiNiche website, I would use something similar to wpon_ (i.e. WordPress OptiNiche).
When it comes time to install another blog using the same database, be sure to repeat the steps being certain to replace the wp_ prefix with something unique for the installation.
That’s really all there is to it!
* If you’re not already familiar with the manual WordPress installation process, I highly recommend watching my WordPress installation video tutorial.
Awesome stuff you’ve been posting these days, Teli.
THANKS
Robert
# May 23rd, 2008
Thanks for the quick, low down tip.
Will have to give this a try when the time comes.
# May 23rd, 2008
Teli,
Could you give me an example of when I might want more than one Wordpress installation for a website, and use only one shared database?
Thanks,
Rich
# June 3rd, 2008
Hi Rich,
You’d want to use a single database if:
1. Your host limits the number of databases you can create.
2. You have quite a few blogs and rather than create 20 databases, it’s much easier to maintain/back up a single one. (Trust me, I know.)
3. If you have more than WordPress installation on a single site and you’d like to organize your databases based on website as opposed to WordPress installations.
I’m sure there are other reasons to use a single database, but those are the ones which jump out at me.
~ Teli
# June 4th, 2008
Thanks for the reply Teli-
I’m a newbie, just getting started with Wordpress, blogging, etc with the goal to have multiple sites/blogs about various, often unrelated, topics. Ultimately I want to make some money with my blogs too.
I was under the impression that different blogs, on different topics, etc, needed a separate database for each. For instance, to monitor site traffic to each blog? Also, is there a possiblity of information for one blog somehow being displayed on another blog using the same database?
Finally, when you have a choice, do you prefer a single shared database over one for each blog? (I guess that you do).
Pardon my ignorance!
Thanks again,
Rich
# June 4th, 2008
Hi again Rich
Short answer, nope. Your site traffic stats don’t necessarily interact with your database–depending on the tool you use. Besides a WordPress plugin (which would still use that particular blog’s WP DB tables anyway), the stats would be stored outside of your database or in its own set of tables. And no, as long as you remember to change the prefix for each installation, you don’t need to worry about information being shared between blogs.
Well, it truly depends on my ultimate purpose for the website itself (for instance, if I plan to build it into something huge, then I’ll use a separate DB), but in general, I prefer to use a single DB for all my blog sites. I find it’s much easier to keep track of that way.
~ Teli
# June 4th, 2008
Teli,
i want to have 3 column and 2 column pages on my blog. i have a neat theme which goes in two versions (3c, 2c).
is your solution the way to go for making this possible?
is it possible at all?
all the best,
adam (@wembley on twitter)
# June 5th, 2008
Hi Adam,
If I understand you correctly, then no this solution wouldn’t work for you. And yes, it is possible, however, it’s wholly incumbent upon your theme.
You’d need to customize your theme so that it will show/hide the third column depending on which page is being viewed. I recommend reading up on WordPress conditional tags for a better understanding.
I hope that gets you pointed in the right direction.
~ Teli
# June 5th, 2008
A friend of mine use that feature because all he needs is to backup one database to save the entire blogs’ data.
I prefer each blog has its own database though.
# July 3rd, 2008
I did this a month back and it works great, just today I updated my hosting which now offers more databases and I would like to delete my old attached install and start fresh which brings me to my question:
How can I uninstall one of the multiple instances without destroying the whole blog?
# July 31st, 2008
This may seem like a strange question, but is it possible for WordPress and WordPress MU to share a database? I want to install MU on a site that has a pre-existing WP blog.
# September 5th, 2008
Hello Shannon,
Yes, just make sure they have a distinct prefix. Open up the MU config file and make sure to change it to something other than ‘wp_’; ‘wpmu_’ would be a better option.
~ Teli
# September 7th, 2008