What does TypeORM upsert do for creating if it does not already exist?

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When using TypeORM's upsert (also known as createQueryBuilder().insert().onConflict().execute()), if a record with the given unique constraint already exists in the database, it will update the existing record with the values provided. Otherwise, it will create a new record with the provided values. In other words, upsert will attempt to insert a new record, but if a record with the same unique key already exists, it will instead update the existing record with the new values.