Using LEFT JOIN of users to transactions, return user_id and COALESCE(COUNT(t.transaction_id), 0) AS

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

Domain

SQL

Difficulty

medium

Problem

Using LEFT JOIN of users to transactions, return user_id and COALESCE(COUNT(t.transaction_id), 0) AS tx_count (users with no transactions get 0). Group by user_id. Order by tx_count ASC, user_id.

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