将 2 个查询的结果合并为 1 个相同的组

Question

enter code here我有 2 个查询使用 2 tables，订单和用户：

--Q1           

SELECT city , AVG(number_of_food_orders_last_month)
FROM (
  SELECT o.city,o.user_id, count(*) AS number_of_food_orders_last_month
  FROM orders AS o
  where bla..bla..                                
  GROUP BY o.city,o.user_id 
)                                                                          
GROUP BY city      
ORDER BY city  
                                                      
--Q2

SELECT o.city, count(distinct u.id) 
FROM users as u 
INNER JOIN orders AS o 
ON o.user_id=u.id
WHERE bla bla IN (
          SELECT id
          FROM users 
          WHERE bla..bla            
)                                                        
GROUP BY o.city
ORDER BY o.city

它们按订单的城市分组 table 所以我想将 2 个查询的结果输出到一个结果中 table。我该怎么做？我试过 UNION 但它不起作用。也许我做错了。

Example:
Q1 outputs:
city    avg
Madrid   1.00
Malaga   2.00
Murcia   1.00
Valencia 3.00

         
Q2 outputs:
 city    count
Madrid   6
Malaga   4
Murcia   10
Valencia 8
            
I want:
 city    count  avg
Madrid   6      1.0
Malaga   4      2.0
Murcia   10     1.0
Valencia 8      3.0

Answer 1

你应该加入他们：

SELECT *
FROM
(
--Q1           

SELECT city AS cityQ1 , AVG(number_of_food_orders_last_month) as average_number_of_food_orders_last_month
FROM (
  SELECT o.city,o.user_id, count(*) AS number_of_food_orders_last_month
  FROM orders AS o
  where bla..bla..                                
  GROUP BY o.city,o.user_id 
)     AS average_number_of_food_orders_by_user_last_month                                                                     
GROUP BY city      
ORDER BY city  
) Q1 
INNER JOIN 
(
--Q2

SELECT o.city as cityQ2, count(distinct u.id) as count_users
FROM users as u 
INNER JOIN orders AS o 
ON o.user_id=u.id
WHERE bla bla IN (
          SELECT id
          FROM users 
          WHERE bla..bla            
)                                                        
GROUP BY o.city
ORDER BY o.city
) Q2 ON Q1.cityQ1 = Q2.cityQ2

如果您可以将城市 ID 添加到 Q1 和 Q2 中，那么加入而不是城市名称会更好。

将 2 个查询的结果合并为 1 个相同的组

combine result of 2 queries into 1 with same group by

sql

union

join