[英]Mysql2::Error: View's SELECT contains a subquery in the FROM clause
[英]View's SELECT contains a subquery in the FROM clause
我有兩個表,我需要創建一個視圖。 這些表是:
credit_orders(id, client_id, number_of_credits, payment_status)
credit_usage(id, client_id, credits_used, date)
我使用以下查詢來執行此操作。 沒有“創建視圖”部分的查詢運行良好,但使用“創建視圖”時,它顯示錯誤“視圖的 SELECT 包含 FROM 子句中的子查詢”。 可能是什么問題和可能的解決方案:
create view view_credit_status as
(select credit_orders.client_id,
sum(credit_orders.number_of_credits) as purchased,
ifnull(t1.credits_used,0) as used
from credit_orders
left outer join (select * from (select credit_usage.client_id,
sum(credits_used) as credits_used
from credit_usage
group by credit_usage.client_id) as t0
) as t1 on t1.client_id = credit_orders.client_id
where credit_orders.payment_status='Paid'
group by credit_orders.client_id)
create view view_clients_credit_usage as
select client_id, sum(credits_used) as credits_used
from credit_usage
group by client_id
create view view_credit_status as
select
credit_orders.client_id,
sum(credit_orders.number_of_credits) as purchased,
ifnull(t1.credits_used,0) as used
from credit_orders
left outer join view_clients_credit_usage as t1 on t1.client_id = credit_orders.client_id
where credit_orders.payment_status='Paid'
group by credit_orders.client_id)
正如關於 視圖限制的最新 MySQL 文檔所說:
在 MySQL 5.7.7 之前,不能在視圖的 FROM 子句中使用子查詢。
這意味着,選擇 MySQL v5.7.7 或更新版本或將現有 MySQL 實例升級到這樣的版本,將完全取消對視圖的這種限制。
但是,如果您的當前生產 MySQL 版本早於 v5.7.7,那么取消對視圖的這種限制應該只是在決定是否升級時評估的標准之一。 使用其他答案中描述的變通技術可能是更可行的解決方案 - 至少在短期內是這樣。
在我看來,MySQL 3.6 給出了以下錯誤,而 MySQL 3.7 不再出錯。 我還沒有在文檔中找到有關此修復程序的任何內容。
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