有没有更好的方法来执行此 SQL 查询？

Question

我写了这个 SQL 查询来为我的数据库中的每个客户获取数据。

如您所见，我正在尝试获取未付款订单总数和我查询的订单总数。

我最后的目标是只获得未付款订单的用户（我想我必须在查询结束时用 HAVING 来实现）。

这是我的查询

SELECT 
u.id, 
u.first_name, 
u.last_name, 
u.email, 
u.phone, 
(SELECT COUNT(*) FROM account_order WHERE account_order.user_id = u.id AND account_order.is_paid = False AND account_order.max_meals > 0) as total_not_paid,
(SELECT COUNT(*) FROM account_order WHERE account_order.user_id = u.id) AS total_orders
FROM account_user u

您认为有更好的方法来获取记录吗？

我怎样才能获得只有一个 total_not_paid 和一个 total_order 的用户？

Answer 1

您可以按如下方式使用条件聚合：

SELECT u.id, u.first_name,  u.last_name, u.email, u.phone, 
       count(case when ao.is_paid = False AND ao.max_meals > 0 then 1 end) 
         as total_not_paid,
       count(ao.*) AS total_orders
  FROM account_user u
  left join account_order ao on account_order.user_id = u.id
  group by u.id;

Answer 2

如果您想要未付款订单，您可以使用显式聚合和 having 子句：

SELECT u.*,
       COUNT(*) FILTER (WHERE NOT is_paid AND ao.max_meals > 0) as total_not_paid,
       COUNT(*) AS total_orders
FROM account_user u JOIN
     account_order ao
     ON ao.user_id = u.id
GROUP BY u.id
HAVING COUNT(*) FILTER (WHERE NOT is_paid AND ao.max_meals > 0) > 0;

有没有更好的方法来执行此 SQL 查询？

Is there a better way to execute this SQL query?

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