Gerador de upsert

Upsert no MySQL: INSERT … ON DUPLICATE KEY UPDATE

Nomeie tabela, chave e colunas e receba a instrução que o MySQL realmente aceita, com uma guarda para que uma linha antiga nunca sobrescreva uma nova. Abaixo: como a mecânica funciona, o que quebra e como a Datrise carrega o MySQL de forma incremental.

As notas técnicas desta página estão em inglês.

Gere a instrução

Instrução · INSERT … ON DUPLICATE KEY UPDATE

INSERT INTO `deals` (`id`, `name`, `stage`, `amount`, `owner_id`, `updated_at`)
SELECT s.`id`, s.`name`, s.`stage`, s.`amount`, s.`owner_id`, s.`updated_at`
FROM `deals_staging` AS s
ON DUPLICATE KEY UPDATE
  `name` = IF(`deals`.`updated_at` < s.`updated_at`, s.`name`, `deals`.`name`),
  `stage` = IF(`deals`.`updated_at` < s.`updated_at`, s.`stage`, `deals`.`stage`),
  `amount` = IF(`deals`.`updated_at` < s.`updated_at`, s.`amount`, `deals`.`amount`),
  `owner_id` = IF(`deals`.`updated_at` < s.`updated_at`, s.`owner_id`, `deals`.`owner_id`),
  `updated_at` = IF(`deals`.`updated_at` < s.`updated_at`, s.`updated_at`, `deals`.`updated_at`);

Como o upsert funciona no MySQL

MySQL's upsert is INSERT … ON DUPLICATE KEY UPDATE. It triggers on any PRIMARY KEY or UNIQUE index violation, and the UPDATE branch can reference the row that failed to insert. The generated form selects from a staging table aliased as s and updates each column from s, wrapped in IF() so a row with an older updated-at leaves the stored values alone.

Two things trip people up. Affected-rows counts 1 for an insert, 2 for an update and 0 for a no-op, which matters when a driver uses it to report success. And InnoDB reserves an auto-increment value for every attempted insert, so a table upserted daily shows gaps in surrogate ids; that is expected, not a lost row. Use utf8mb4 on the target so CRM text with emoji survives the write.

Antes de executar

"Duplicate" means any PRIMARY KEY or UNIQUE index, not just the one you think of as the business key. A second unique index on email will silently merge rows you meant to keep apart.
The IF() guard keeps the existing row when the incoming updated-at is older. Without it the last write wins, whatever its timestamp.
Avoid REPLACE INTO for upserts: it deletes and re-inserts, which fires DELETE triggers, cascades foreign keys and burns auto-increment values.

Perguntas frequentes

Why does ON DUPLICATE KEY UPDATE merge rows I did not expect?

It fires on every unique index, not only the primary key. A unique index on email will fold two contacts with the same address into one. Drop or relax secondary unique indexes on synced tables.

REPLACE INTO or ON DUPLICATE KEY UPDATE?

ON DUPLICATE KEY UPDATE. REPLACE deletes the old row and inserts a new one, which fires DELETE triggers, cascades foreign keys and changes the auto-increment id.

Is VALUES(col) still valid?

It works but is deprecated since MySQL 8.0.20. Referencing the staging alias (s.col) as generated, or the INSERT … AS new alias form, is the supported syntax.

O mesmo gerador para outros destinos

Pule a escrita do merge

A Datrise entrega entidades de CRM e SaaS no MySQL com exatamente esta mecânica, uma marca d'água sobre updated-at e colunas tipadas, então a instrução acima é a que roda por você. Entre na lista de espera para acesso antecipado.

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