LEFT JOIN + IS NULL

Anti-join — rows in A with no match in B

SQL drill • Joins

Find customers who have never placed an order.
customers(id, name), orders(id, customer_id, ...). Return customer names only.
Supporting drill: SQL is not usually the whole interview, but join literacy shows up next to JOIN + GROUP BY and window questions.

Pattern
LEFT JOIN + WHERE B.key IS NULL

Step 0/6Line —

Preserved left row NULL padding (no match)

Conceptual evaluation

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LEFT JOIN keeps every left row; missing right side becomes NULL — filter those.

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Check expects LEFT JOIN, ON, WHERE, and IS NULL on the right key.

══ LEFT ANTI (NOT EXISTS feel) ══

FROM customers c

LEFT JOIN orders o ON c.id = o.customer_id

WHERE o.id IS NULL — no order row matched

YOUR QUERY

Verify: