Write Your First SQL JOIN: THE LAB

THE LAB is chapter 8, where you write your first SQL JOIN. Operation ATLAS links field agents to their mission assignments: the MISSIONS table carries an AGENT_ID column, and INNER JOIN with ON matches it against AGENTS.ID to reveal who did what.

The warm-up mission works the HANDLER_MEETINGS log, grouping contact records per handler and sorting the busiest first, so the jump to two-table queries lands on a solid GROUP BY foundation.

Joins are the single most tested skill in data interviews. This chapter is where SQL Protocol starts drilling them, and the joins guide linked below is the companion reading.

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 AGENTS.CODENAME, MISSIONS.MISSION_NAME
FROM AGENTS
INNER JOIN MISSIONS ON AGENTS.ID = MISSIONS.AGENT_ID
WHERE MISSIONS.PRIORITY = 'LOW';

Free guides that pair well with this chapter:

• SQL Joins Explained: INNER, LEFT, RIGHT, FULL