You can use the built in database viewer to view the tables of you database.
It is possible but not recommended to edit your tables outside of the mendix runtime as it can lead to data corruption in your database.
Hope this helps with your question!
Hope you are doing well.
In Mendix, for a persistable entity a table will be created via DDL commands which will run at the very first time you run your code ,if the the database other then build-in HSQL database you can query your database directly for the System.User table , and list down all the existing users within your application.
But within Mendix modeler you cannot view users list without running your server or when the app is not running locally.
Thanks ,kindly respond for any further clarification.
You can access the built in database while your app is running.
If you're using the built-in database the modeler has an option in the console screen under the advanced menu called Start built-in database viewer. With this viewer you can access the database.
Here's a documentation for it: