online database viewer [Python - flask] based *

hello I need to create a simple web app similar to [login to view URL] where all i need for now is the back-end of it so don't worry much about the front end but I need users who can access this feature must be registered and logged in which means Clients might be connected to two database or more 1 - the login database / user data on my website. 2 - their own database and be able to pull all database information from it like ( tables name , columns , rows , data in each cell ... etc ) Should works with all type of databases ( MySql , Sqlite , PostgreSQL ..etc ) ( * ) only user in session should be able to access his/her database and never the others so Security is Critical in this code.