QuerydrillSignups per plan
An SQL exercise from Querydrill. Solve it with a SQL editor in your browser, checked on the rows it returns and again on changed data, and it is checked the moment you submit.
The task
From Leo in Product: "How many signups are on each plan? Write the plan names in lowercase, and count signups without a plan as unknown." Return plan and signups.
What this exercise teaches
Missing values disappear quietly from many reports. Naming them, here as unknown, keeps the totals honest.
A hint if you get stuck
COALESCE(LOWER(TRIM(plan)), 'unknown') turns NULL into the word unknown. Group by that same expression.
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