Q: SQL query. (Join, Group by, Order by)

Q: Coding challenge was to connect front end with backend. Basically before the interview day, they asked me to have two sample project ready, one for back end (java) and one for front end (react/angular). On the interview day, with a screen share, they gave me the task to add some java rest end point to return some text and from the front end to call the end point to display the text. There was a bonus question if it handles null or empty string.