Local Drupal 7 user in database I want to save a user's email and username when a button is clicked.
I assume I have to do this via PHP but I can find the user column at localhost/phpmyadmin. Where is the users' information being stored and which is the MySQL query to achieve that?
You should not use a direct MySQL query to update anything.

In this case you can use user_save(); which it is basically, load the user object -&gt; change data -&gt; pass it to user_save(); or even better user entityAPI and entity_metadata_wrappers

The default table where drupal saves user data is users, there you can find the email and username