Symmetric Reply Network

A medium SQL interview practice problem on DataDriven. Write and execute real sql code with instant grading.

Domain

SQL

Difficulty

medium

Seniority

L3

Problem

The chat_messages table has sender and reply_to columns. Produce a symmetric view of the reply network: if user A replied to user B, the output should include both (A, B) and (B, A). Show each pair of user IDs.

Summary

Who replies to whom? Both directions.

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