Code RoomComment count per post
MediumPrep Room Coding #5090

Comment count per post

SQLAlgorithms & data structuresMid~10 min

Return every post with how many comments it has. Give `title` and `comments`, most commented first, then by title. Posts with none show 0.

What a strong answer looks like

Say what the query is meant to return before you write it, and name the shape of the answer: how many rows, grouped by what. Then watch the NULLs and the duplicates, because that is where most of these are lost.

Run onlyA query runs as one statement, so there is nothing to step through. Run it and read the rows.

0:00 of about 10 min

Expected, in this order

titlecomments
Indexes explained3
Replication lag1
Vacuum and bloat1
Draft on locks0
Query plans0

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