# The Missing Water Drill

THE GREAT DUCK MIGRATION! · challenge 39 · medium

> Coach Waddles taps the swimming roster with a dripping feather. "These ducks were in the water in 2024, Duckbert. In 2025? Not a single lap! A flying medal won't get anyone across the rapids. Find the ducks who swam in 2024 but haven't entered a single swimming competition in 2025. Sum their identification codes so I can call them back for a refresher before we depart!"

## Task

Return the sum of SSNs for all ducks who competed in swimming at least once during 2024 but never competed in swimming during 2025. A duck still qualifies if it competed in other sports during 2025 or did not compete at all in 2025. Count each duck only once. You will be working with the `duck_athletes` and `performance_records` tables.

## Tables

### `performance_records` (800 rows)

| column | type |
| --- | --- |
| duck_id | BIGINT |
| sport | VARCHAR |
| score | DOUBLE |
| competition_date | DATE |

### `duck_athletes` (50 rows)

| column | type |
| --- | --- |
| id | BIGINT |
| ssn | BIGINT |
| name | VARCHAR |
| age | BIGINT |
| hometown | VARCHAR |

## Data

The tables live in a DuckDB database: https://dbquacks.com/data/databases/athletic_champions.duckdb

To query it outside the browser, attach it read-only:

```sql
ATTACH 'https://dbquacks.com/data/databases/athletic_champions.duckdb' AS db (READ_ONLY);
USE db;
```

Play it in the browser: https://dbquacks.com/challenges/athletic/39

## Answer

The expected answer is not published. Submit on the page to have it checked.