Query sample with first and last name for every user:
SELECT users.user_login, users.user_email, users.user_registered, meta1.meta_value as first_name, meta2.meta_value as last_name
FROM wp_users users
INNER JOIN wp_usermeta as meta1 on meta1.user_id=users.ID and meta1.meta_key='first_name'
INNER JOIN wp_usermeta as meta2 on meta2.user_id=users.ID and meta2.meta_key='last_name'
