Filter with EXISTS

sql

SELECT c.customer_id
FROM customers c
WHERE EXISTS (
  SELECT 1
  FROM orders o
  WHERE o.customer_id = c.customer_id
);

Explanation

EXISTS is often efficient for existence checks.

Learn the surrounding workflow

Compare similar commands or jump into common fixes when this command is part of a bigger troubleshooting path.

Same sheet · prioritizing EXISTS and Set Operations

Return rows with no related matches.

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Return rows present in both queries.

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Return rows from the first query not present in the second.

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Filter rows based on results from another query.

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