Meta-style Company ChallengeEasyVerified answerSQLite live

Users Who Have Never Posted

Which registered users have never created a single post?

  • Joins
  • NULL handling
  • Filtering
  • Sorting

Challenge brief

Understand the request

Growth Team is running a 'share your first post' campaign and needs users who registered but never published any content.

Find users with zero posts using an anti-join.

Return

  • user_id
  • username
  • email
  • country

Constraints

  • Return registered users with no posts
  • Order by user ID

Data you will use

Review the relevant tables before deciding how to join, filter, or aggregate them.

users

  • user_idINTEGER
  • usernameVARCHAR(50)
  • emailVARCHAR(100)
  • countryVARCHAR(50)

posts

  • post_idINTEGER
  • user_idINTEGER

Hints, when you need them

Open one clue at a time so you still do the reasoning.

Hint 1

You need users with NO matching rows in posts. This is an anti-join: LEFT JOIN users to posts, then keep only rows where the posts side is NULL — meaning no post was found for that user.

Hint 2

LEFT JOIN users to posts on user_id. WHERE p.post_id IS NULL keeps only users with no matching post row.

Hint 3

Start with the tables that establish the result grain for question 18, select the required output aliases, and add the remaining joins, filters, aggregation, and ordering one clause at a time.

Verified SQL answer

Attempt the problem first, then compare structure and reasoning—not just syntax.

Reveal solution and explanation
SELECT u.user_id, u.username, u.email, u.country FROM users u LEFT JOIN posts p ON u.user_id = p.user_id WHERE p.post_id IS NULL ORDER BY u.user_id

Why this works

LEFT JOIN keeps all users even with no posts. Unmatched rows have NULL in all posts columns. WHERE post_id IS NULL isolates zero-post users — the anti-join pattern. alex_brown is the only one.

Success check

1 user — alex_brown (the only user with zero posts)

Expected result

Use this output to verify values, aliases, ordering, and row count.

user_idusernameemailcountry
5alex_brownalex@email.comAustralia

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