Find customers who have never ordered.
Section: Anti-joins
Use NOT EXISTS for anti-join behavior
sql
sql
SELECT c.customer_id, c.name
FROM customers c
WHERE NOT EXISTS (
SELECT 1
FROM orders o
WHERE o.customer_id = c.customer_id
);Explanation
`NOT EXISTS` is usually the safest anti-join pattern.
Learn the surrounding workflow
Compare similar commands or jump into common fixes when this command is part of a bigger troubleshooting path.
Related commands
Same sheet · prioritizing Anti-joins
LEFT JOIN ... IS NULL anti-join
Find unmatched rows by outer join plus null check.
Be careful with NOT IN and NULLs
A single `NULL` in the subquery can change results in surprising ways.
Use EXISTS for semi-join behavior
Return customers who have at least one order without duplicating customer rows.
Use IN for simple membership checks
Another semi-join style when selecting from a single column set.