D8LooPFocus modeCODE WORKSPACE
Detect upsert key violations
Find null and duplicate unique keys that would make an upsert unsafe.
The SQL API will hydrate this workspace with the exercise-specific starter query and schema.
Sample input
customer_stageThe merge/upsert key must identify one target row. Here customer_id 104 is duplicated and one row has no key.
| customer_id | updated_at | |
|---|---|---|
| 104 | dee-old@example.com | 2026-03-05 09:00:00 |
| 104 | dee@example.com | 2026-03-05 12:30:00 |
| null | ghost@example.com | 2026-03-05 13:00:00 |
Expected output
Expected outputReport unsafe keys before any merge: duplicate customer 104 and one NULL key.
| issue_type | customer_key | rows_in_batch |
|---|---|---|
| duplicate_key | 104 | 2 |
| null_key | <NULL> | 1 |
Constraints
Load the live SQL exercise to inspect the full prompt, schema, starter query, and expected output.
Expected skills
Upserts, Unique keys, HAVING
SQL
Loading...
AI evaluation
Run the SQL query to inspect preview rows.