Depends on where you updated...if you used your phone to update but also have the app in your iTunes library, you should be able to delete the updated version from your phone and then resync with iTunes, which will simply put the older version that it still has back on your device.
If you updated in iTunes, then the older version is likely in your Recycle Bin/Trash...in that case you'd need to first delete the new one from your phone, then delete the new one from iTunes and Restore the older version to iTunes, then sync. Make sense?
Of course, there is always the possibility that it isn't the app that's buggy, but something that it uses in the cloud. That "database problem" makes me wonder...have you tried deleting and reinstalling the update?