Users in the Database

Assuming your $table_prefix in wp-config.php is ‘wp_’

That mapping of role to user is handled via a row in wp_usermeta with each user_id and the meta_key wp_capabilities

Also see Roles and Capabilites and check the Resources section of that article for plugins that deal with the topic.

Thanks so much MichaelH …that was very helpful.

One thing I still don’t understand however is how to interpret the wp_capabilities string. For example, this:

a:1:{s:10:”subscriber”;b:1;}

…looks like seven or eight colon-delimited fields describing capabilities somehow but I don’t see the documentation of it anywhere on the “Roles and Capabilities” page.

Or perhaps I should work instead with a function that simply gets the capabilities from the database and returns them to me so that my code can say “Oh now I see what this user can and can’t do”. Either way is fine by me.

That’s a serialized string – look at one of those plugins I was talking about…also some other stuff:
https://www.shinephp.com/how-to-change-wordpress-user-role-capabilities/
https://phpdoc.www.ads-software.com/trunk/WordPress/User/WP_User.html
https://svn.automattic.com/wordpress-tests/wp-testcase/test_user_capabilities.php
https://www.google.com/search?q=wordpress+wp_user+wp_role