Suppose there is a table named messages with columns id, sender_id, receiver_id, and message. What is the approach you would take to determine the set of distinct communicators?

Hard Difficulty

Hard questions require advanced understanding and critical thinking. Here, your problem-solving skills are key, as these questions often involve complex scenarios needing in-depth analysis and well-structured responses.

SQL question

SQL questions test your ability to work with relational databases. Demonstrate your proficiency in writing queries, understanding database design, optimizing performance, and extracting meaningful information from structured data.

Here's a Hint

Consider using UNION or combining sender_id and receiver_id, with attention to avoiding duplicates when the same two people communicate multiple times.