Christian1012 on "User_login from wp_users to wp_usermeta"

I don't think that's really what you want to do. They are in different tables for a reason, why would you want to duplicate tables in the same database?

Can't you just include it in your query? Example:

SELECT wp_usermeta . * , wp_users.user_login
FROM wp_usermeta
INNER JOIN wp_users ON wp_usermeta.user_id = wp_users.ID
WHERE wp_usermeta.user_id = 1;