What is an upsert?

SQL changing data safely · Freshers and experienced

Model answer

Insert a row, or update it if it already exists. PostgreSQL and SQLite use INSERT ... ON CONFLICT (key) DO UPDATE, MySQL uses ON DUPLICATE KEY UPDATE, and standard SQL has MERGE. It needs a unique key and avoids race conditions of check-then-insert.

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INSERT, UPDATE and DELETE: Change Data Safely in the course SQL for Beginners: Learn Databases Step by Step.

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