Question

我一直在尝试删除重复的记录（shopify_order_id列中的值相同），并保留最新的记录。

我在sql中写的：

select orders.id from (
  select shopify_order_id, min(shopify_created_at) as min_created 
  from orders group by shopify_order_id having count(*) > 1 limit 5000
) as keep_orders 
join orders 
on 
  keep_orders.shopify_order_id = orders.shopify_order_id and 
  orders.shopify_created_at <> keep_orders.min_created

，现在我正尝试将其添加到Active Record，但似乎无法将这两部分结合在一起。

第一个嵌套选择是

Order.select('shopify_order_id, MIN(shopify_created_at) as min_created').
        group(:shopify_order_id).
        having('count(*) > 1').
        limit(5000)

，但是以下操作无效：

Order.select('orders.id').from(keep_orders, :keep_orders).
joins('orders ON keep_orders.shopify_order_id = orders.shopify_order_id').
where.not('orders.shopify_created_at = keep_orders.min_created')

它建立查询：

SELECT  orders.id FROM  (SELECT  shopify_order_id, MIN(shopify_created_at) as min_created FROM "orders" GROUP BY "orders"."shopify_order_id" HAVING (count(*) > 1) LIMIT $1) keep_orders  orders ON keep_orders.shopify_order_id = orders.shopify_order_id WHERE NOT (orders.shopify_created_at = keep_orders.min_created) ORDER BY "orders"."id" ASC LIMIT $2  [["LIMIT", 5000], ["LIMIT", 1]]

缺少关键字join。

任何有关如何重构查询/以其他方式执行查询的帮助将不胜感激。

Answer 1

如果用string SQL fragment呼叫joins，则需要指定所需的联接类型：

Order.select('orders.id').from(keep_orders, :keep_orders)
  .joins('JOIN orders ON keep_orders.shopify_order_id = orders.shopify_order_id')
  .where.not('orders.shopify_created_at = keep_orders.min_created')

删除重复的记录，保留上次使用的ActiveRecord

1 个答案: