Unassigned Locker Numbers
Problem
A gym assigns lockers to members with sequential locker numbers, but some numbers in the sequence are currently empty. The `Locker` table holds the assigned lockers.
`Locker`:
- `locker_no` (int) — an assigned locker number
- `holder_name` (varchar)
Return every locker number between 1 and the largest assigned `locker_no` that is **not** currently assigned. Name the single output column `gap_no`.
Tables
Example rows — the live problem includes the full dataset.
Locker
| locker_no | holder_name |
|---|---|
| 1 | Hugo |
| 4 | Iris |
| 5 | Jonas |
Expected output
Your answer should return 2 rows with the columns gap_no.
Starter code (SQL)
SELECT *
FROM Locker;Solve this SQL question free
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Solution & explanation
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