如何將兩個MySQL查詢的結果合並為一個？

Question

假設我有一個這樣的表：

如何計算每個人在2018-09-07當天發生的數據數量以及每個人在2018-09月份發生的數據數量？

我的意思是我想創建一個像這樣的表：

我知道

SELECT 
  name, 
  COUNT(*) AS day_count_2018_09_07
FROM data_table
WHERE 
  arrive_time >= '2018-09-07 00:00:00'
  AND
  arrive_time <= '2018-09-07 23:59:59'
GROUP BY name;

可以生成每個人在2018年9月7日當天發生的數據數量，並且

SELECT 
  name, 
  COUNT(*) AS month_count_2018_09
FROM data_table
WHERE 
  arrive_time >= '2018-09-01 00:00:00'
  AND
  arrive_time <= '2018-09-30 23:59:59'
GROUP BY name;

可以生成每個人在2018-09月份發生的數據數量。

但我不知道如何將上述兩個查詢結合，從而day_count_2018_09_07和month_count_2018_09列可以在一個查詢中創建。

這是SQL提琴 ，您可以在其中直接獲取問題中的數據。

Answer 1

您可以使用條件聚合從同一查詢中獲得兩個結果：

SELECT name, 
   SUM(CASE WHEN SUBSTR(DATE(arrive_time),1,7)='2018-09' THEN 1 ELSE 0 END) AS month_count_2018_09,
   SUM(CASE WHEN DATE(arrive_time)='2018-09-07' THEN 1 ELSE 0 END) AS day_count_2018_09_07
FROM data_table
GROUP BY name

輸出：

name    month_count_2018_09     day_count_2018_09_07
Ben     3                       0
Jane    1                       1
John    3                       2

Answer 2

嘗試像這樣合並它們：

Select DayCounter.name, DayCounter.day_count_2018_09_07, MonthCounter.month_count_2018_09
from
(SELECT 
  name, 
  COUNT(*) AS day_count_2018_09_07
FROM data_table
WHERE 
  arrive_time >= '2018-09-07 00:00:00'
  AND
  arrive_time <= '2018-09-07 23:59:59'
GROUP BY name) as DayCounter
Inner Join
(SELECT 
  name, 
  COUNT(*) AS month_count_2018_09
FROM data_table
WHERE 
  arrive_time >= '2018-09-01 00:00:00'
  AND
  arrive_time <= '2018-09-30 23:59:59'
GROUP BY name) as MonthCounter

On DayCounter.name = MonthCounter.name

Answer 3

像這樣的事情呢：

SELECT
  name,
  SUM(CASE WHEN (arrive_time BETWEEN '2018-09-07 00:00:00' AND '2018-09-07 23:59:59') THEN 1 ELSE 0 END) AS day_count_2018_09_07,
  SUM(CASE WHEN (arrive_time BETWEEN '2018-09-01 00:00:00' AND '2018-09-30 23:59:59') THEN 1 ELSE 0 END) AS month_count_2018_09
FROM
    data_table
GROUP BY
    name;