If you are just starting out and wish to separate content into two or more major categories that are largely unrelated to each other, that can be done by creating top-level groups in a database and filing your documents into subgroups within them.
As your database grows, that will make it easy to split it into multiple databases, each corresponding to the content of one of those top-level groups.
Examples of procedures to split a database into two or more separate databases:
Create a new, empty database and give it an appropriate name. In the original database, select the content that’s to be moved to the new database and then Control-click (right click) on the selection. Choose the contextual menu option, ‘Move To’ and select the new database as the destination. (The ‘Move To’ command will transfer the selected content to the other database and remove it from the first, in public beta 7 and later.) If you wish to change the name of the original database, read about how to do that in 2), below and start with 2a).
Another way to ‘split’ databases is to make one or more copies of it in the Finder, deleting from each the content that isn’t desired in that database.
2a) First, Quit the DT Pro/Office application. That’s important, as making a Finder copy of an open database may result in an incomplete or damaged copy!
2b) Still in the Finder, and with the DEVONthink application still Quit, rename the copied database if the name is to change. Never rename an open database, as DEVONthink would lose track of it.
2c) Launch DT Pro/Office and open, one at a time, each of the database copies. Select and delete from each the content that isn’t desired in it.
2d) If the copy was renamed in the Finder, the new database name will not be displayed in view windows until it is changed in File > Database Properties.
2e) If all of the resulting split databases have a different name than did the original, clear DEVONthink’s memory of the original database by selecting File > Open Recent and choose the option to clear the menu.