Learn DISTINCT and CASE WHEN: THE EXCHANGE

THE EXCHANGE is chapter 4. Its missions run on the OPERATIVES table: CODENAME, POSTING, LOYALTY_SCORE, MISSIONS_COMPLETED, and YEARS_ACTIVE. Multiple operatives share the same stations, so the first job is SELECT DISTINCT to collapse duplicate postings into a clean list.

Then comes conditional logic. Using CASE WHEN, you translate each LOYALTY_SCORE into a verdict, bucketing operatives into categories the station chiefs can act on. It is the same expression working analysts use every day to turn raw numbers into labels.

Type the query, watch the rows come back, and let the server judge whether your classification holds.

This is the shape of query you practice here, not the answer to any mission. The real stages come with their own data, objectives, and hints.

SELECT CODENAME,
  CASE WHEN LOYALTY_SCORE >= 90 THEN 'TRUSTED'
       ELSE 'REVIEW'
  END AS VERDICT
FROM OPERATIVES;

Free guides that pair well with this chapter:

• GROUP BY and HAVING: The Difference Explained