Database powered applications are supported by flask. The relational database systems need to create a schema that requires piping the schema.sql file into a SQLite3 command. So, in this case you need to install SQLite3 command on your system to initiate and create the database in the flask.
We can request a database using flask in three ways, and they are:
before_request(): Using this we can request database before only without passing arguments.
after_request(): This method is called after requesting the database and also send the response to client.
teardown_request(): This method is called in the cases where the responses are not guaranteed and the exception is raised. They have no access to modify the request.