Question

我需要将这些查询组合在一起，因此我会返回一个月份列表，其中包含新的总数和返回的总数（用于跟踪新用户和返回用户）。我目前在下面有这两个问题。第一个计数是新的设备（检测频率），第二个计数为返回。我想输出结果，因此它是一个包含每个月行的表，然后是两列包含New和Returning数据。

SELECT COUNT( DISTINCT (mac) ) AS new,
EXTRACT( MONTH FROM date_time ) AS month
FROM detected_devices
WHERE client_id = 11
AND venue_id = 1
AND detection_frequency = 1
GROUP BY month

UNION ALL

SELECT COUNT( DISTINCT (mac) ) AS returning,
EXTRACT( MONTH FROM date_time ) AS month
FROM detected_devices
WHERE client_id = 11
AND venue_id = 1
AND detection_frequency > 1
GROUP BY month

我已经浏览了一下，但没有找到任何有关如何使用别名来完成此操作的信息。

Answer 1

这个怎么样？

SELECT t1.month, t1.new, t2.returning FROM (query 1) as t1, (query 2) as t2 where t1.month = t2.month;

（或加入，取决于您的喜好）。

Answer 2

这只会给你一行有两列，但应该让你知道如何使用别名

SELECT
A.new,
B.returning
FROM
(SELECT COUNT( DISTINCT (mac) ) AS new,
EXTRACT( MONTH FROM date_time ) AS month
FROM detected_devices
WHERE client_id = 11
AND venue_id = 1
AND detection_frequency = 1
GROUP BY month) A,
(SELECT COUNT( DISTINCT (mac) ) AS returning,
EXTRACT( MONTH FROM date_time ) AS month
FROM detected_devices
WHERE client_id = 11
AND venue_id = 1
AND detection_frequency > 1
GROUP BY month) B

结合这些mySQL查询

2 个答案: