MERGE / UPSERT Statement

-- PostgreSQL: INSERT ... ON CONFLICT (upsert)
INSERT INTO products (sku, name, price, updated_at)
VALUES ('ABC-123', 'Widget', 29.99, NOW())
ON CONFLICT (sku)
DO UPDATE SET
  name = EXCLUDED.name,
  price = EXCLUDED.price,
  updated_at = EXCLUDED.updated_at;

-- SQL Server / Oracle: MERGE
MERGE INTO products AS target
USING staging AS source
  ON target.sku = source.sku
WHEN MATCHED THEN
  UPDATE SET
    name = source.name,
    price = source.price
WHEN NOT MATCHED THEN
  INSERT (sku, name, price)
  VALUES (source.sku, source.name, source.price);