What is the best full stack tech code example

Example 1: full stack

two general fields that make up a full-stack developer’s skillset: 
front-end development and back-end development.

Example 2: what is full stack

1. create a data (a customer account) on UI
2. send request from API and verify data is 
matching with UI (you reach your database
through API, it is credible as much as 
your API software is credible)
3. send SQL queries using JDBC get request
to database and verify data is
matching with post request