视图的 SELECT 在 FROM 子句中包含子查询

2021-11-20 00:00:00 sql database mysql views

我有两个表，我需要创建一个视图.这些表格是:

I have two tables and I need to create a view. The tables are:

credit_orders(id, client_id, number_of_credits, payment_status)
credit_usage(id, client_id, credits_used, date)

我使用以下查询来执行此操作.没有创建视图"部分的查询运行良好，但使用创建视图"时，它显示错误视图的 SELECT 包含 FROM 子句中的子查询".可能是什么问题&可能的解决方案:

I use the following query to do this. The query without the "create view" part works well but with "create view", it shows the error "View's SELECT contains a subquery in the FROM clause". What could be the issue & possible solution:

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)

推荐答案

根据文档:

MySQL 文档

  • SELECT 语句不能在 FROM 子句中包含子查询.

您的解决方法是为每个子查询创建一个视图.

Your workaround would be to create a view for each of your subqueries.

然后从您的视图中访问这些视图 view_credit_status

Then access those views from within your view view_credit_status

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