Mysql2 ::錯誤：視圖的SELECT在運行rails遷移時在FROM子句中包含子查詢

Question

使用Rails遷移（但並不重要）。我想在這裏創建一個視圖，但我得到了

Mysql2::Error: View's SELECT contains a subquery in the FROM clause: 
CREATE VIEW `lanciao` AS 

當我試試這個：

create view lanciao as 
    select 
    subtime(payment.created_at, '0 5:0:0') as transaction_date, 
    `order_item`.total_quantity, 
    payment.amount as amount, 
    `order`.payment_type 
    from payments payment 
    join orders `order` on `order`.id = payment.order_id 
    left join donation_items donation on donation.order_id = `order`.id 
    inner join (
    select order_id, sum(quantity) total_quantity 
    from order_items 
    group by order_id 
) `order_item` on `order`.id = `order_item`.order_id 
    where payment.payment_state in ('settled', 'completed', 'captured', 'authorized', 'approved') 
    and `order`.fixed_order_id is null 

沒有create view lanciao，我可以運行select塊到最後的罰款。我試圖重構這個，但不能得到它的工作。我應該如何解決這個問題？

我也意識到將這個分隔到不同的視圖並且互相引用，但我不會喜歡這種方式。

Answer 1

的MySQL docs狀態：

Before MySQL 5.7.7, the SELECT statement cannot contain a subquery in the FROM clause.

如果你可以升級到MySQL 5.7.7+，那麼你應該能夠做你想要做什麼。

否則，你可能想嘗試創建子查詢的視圖，然後使用您的FROM。

所以不是你的SQL可能看起來像：

create view subquery_view as 
    select order_id, sum(quantity) total_quantity 
    from order_items 
    group by order_id 

create view lanciao as 
    select 
    subtime(payment.created_at, '0 5:0:0') as transaction_date, 
    `order_item`.total_quantity, 
    payment.amount as amount, 
    `order`.payment_type 
    from payments payment 
    join orders `order` on `order`.id = payment.order_id 
    left join donation_items donation on donation.order_id = `order`.id 
    inner join subquery_view as `order_item` on `order`.id = `order_item`.order_id 
    where payment.payment_state in ('settled', 'completed', 'captured', 'authorized', 'approved') 
    and `order`.fixed_order_id is null 

要知道這裏面相互嵌套的觀點可能會導致性能問題，但我不知道另外的辦法。