并排的两个查询 - 共同的月/年（MYSQL）

Question

我试图将两个查询并排放置，它们之间有共同的月份和年份。 它们可以完美地单独工作。

Table Boxes - 每月寻找盒子

SELECT count(*) AS Count_Boxes,
DATE_FORMAT(create_date, '%b') AS 'Month',
DATE_FORMAT(create_date, '%Y') AS 'Year'
FROM boxes
GROUP BY YEAR(create_date), MONTH(create_date);

表订单 - 每月寻找订单

SELECT count(*) as Count_Orders,
DATE_FORMAT(create_date, '%b') AS 'Month',
DATE_FORMAT(create_date, '%Y') AS 'Year'
FROM orders
GROUP BY YEAR(create_date), MONTH(create_date);

我已经尝试了很多使用 LEFT JOIN 的方法，但没有任何效果。

有什么建议吗？

Answer 1

你可以加入：

SELECT o.count_orders, b.*
FROM (
    SELECT count(*) AS Count_Boxes,
    DATE_FORMAT(create_date, '%b') AS mn,
    DATE_FORMAT(create_date, '%Y') AS yr
    FROM boxes
    GROUP BY YEAR(create_date), MONTH(create_date)
) b
INNER JOIN (
    SELECT count(*) as Count_Orders,
    DATE_FORMAT(create_date, '%b') AS mn,
    DATE_FORMAT(create_date, '%Y') AS yr
    FROM orders
    GROUP BY YEAR(create_date), MONTH(create_date)
) o ON o.mn = b.mn and o.yr = o.yr

但是，如果任何一个数据集都有可能丢失周期，则另一种方法使用union all ：

SELECT 
    SUM(no_orders) count_orders,
    SUM(no_boxes) count_boxes,
    DATE_FORMAT(create_date, '%b') mn,
    DATE_FORMAT(create_date, '%Y') yr
FROM (
    SELECT create_date, 0 no_orders, 1 no_boxes FROM boxes
    UNION ALL       
    SELECT create_date, 1, 0 FROM orders
)
GROUP BY YEAR(create_date), MONTH(create_date)