Meta-style Company ChallengeBeginnerVerified answerSQLite live

Pending Friend Requests

Which friend requests are still waiting to be accepted?

  • Joins
  • Filtering
  • Sorting

Challenge brief

Understand the request

Social Graph Team is monitoring unresolved connection requests to improve the friend-suggestion experience.

List pending friend requests showing sender name, receiver name, and when the request was sent.

Return

  • sender_name (full name)
  • receiver_name (full name)
  • requested_at

Constraints

  • Return friendship requests whose status is 'pending'
  • Show the oldest pending requests first

Data you will use

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

friendships

  • friendship_idINTEGER
  • user_id_1INTEGER
  • user_id_2INTEGER
  • statusVARCHAR(20)
  • requested_atDATETIME

users

  • user_idINTEGER
  • first_nameVARCHAR(50)
  • last_nameVARCHAR(50)

Hints, when you need them

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

Hint 1

The friendships table stores both accepted and pending connections. Filter to 'pending'. User names are in users — join it twice with different aliases for sender and receiver.

Hint 2

JOIN friendships to users twice: u1 ON user_id_1, u2 ON user_id_2. WHERE f.status = 'pending'. Concatenate names with || ' ' ||.

Hint 3

Start with the tables that establish the result grain for question 17, 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 u1.first_name || ' ' || u1.last_name AS sender_name, u2.first_name || ' ' || u2.last_name AS receiver_name, f.requested_at FROM friendships f INNER JOIN users u1 ON f.user_id_1 = u1.user_id INNER JOIN users u2 ON f.user_id_2 = u2.user_id WHERE f.status = 'pending' ORDER BY f.requested_at, f.friendship_id

Why this works

The friendships table uses two FK columns (user_id_1, user_id_2) that both reference users. Two aliases (u1, u2) let you reach each side independently. Only friendship_id 5 (John to Sarah) has status = 'pending'.

Success check

1 pending request — John Doe sent to Sarah Jones (2024-01-18)

Expected result

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

sender_namereceiver_namerequested_at
John DoeSarah Jones2024-01-18 10:00:00

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