MERGE INTO products p

USING product_changes pc

ON (p.product_id = pc.product_id)

WHEN MATCHED THEN  --当匹配上时进行更新操作

  UPDATE

     SET p.product_type_id = pc.product_type_id,

         p.name            = pc.name,

         p.description     = pc.description,

         p.price           = pc.price

WHEN NOT MATCHED THEN  --当不匹配上时进行插入操作

  INSERT

    (p.product_id, p.product_type_id, p.name, p.description, p.price)

  VALUES

    (pc.product_id, pc.product_type_id, pc.name, pc.description, pc.price);