Your question is SQL Value Swapping. Start with the requirements and the two tables on the right.
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Write a SQL query to swap values between two columns or rows.
Use the provided PostgreSQL tables. Swap the two assignment value columns only for assignments referenced by approved swap requests. Preserve all other assignments and return the values before and after the swap.
assignment_id.assignment_id, old_primary_value, old_secondary_value, new_primary_value, and new_secondary_value.| Column | Type | Description |
|---|---|---|
| assignment_idPK | INT | Unique assignment identifier |
| primary_value | VARCHAR(50) | First value eligible for swapping |
| secondary_value | VARCHAR(50) | Second value eligible for swapping |
| Column | Type | Description |
|---|---|---|
| request_idPK | INT | Unique swap request identifier |
| assignment_id | INT | Assignment targeted by the request |
| approved | BOOLEAN | Whether the swap request is approved |