如何將多個選擇結果合併到一個表中？

Question

我有一個查詢，從同一個表中返回的月平均值，但對於不同的pressure_level的：

SELECT some_id, avg(exposure_value) monthly_avg_1000 
FROM mytable 
WHERE pressure_level = 1000 
AND some_id = 7 
GROUP BY some_id, date_trunc('month', measurement_time) 

然後我有相同的查詢，但對於不同的pressure_level：

SELECT some_id, avg(exposure_value) monthly_avg_925 
FROM mytable 
WHERE pressure_level = 925 
AND some_id = 7 
GROUP BY some_id, date_trunc('month', measurement_time) 

兩個查詢返回12行（每月1）與ID和本月的平均值：

some_id | monthly_avg_1000 
-------------------------- 
1  | 0.000023 
1  | 0.000051 
1  | 0.000009 

some_id | monthly_avg_925 
-------------------------- 
1  | 0.000014 
1  | 0.000007 
1  | 0.000131 

我想結合這兩個查詢，所以噸帽子的monthly_avg_ *列都出現在決賽桌上：

some_id | monthly_avg_1000 | monthly_avg_925 
-------------------------- 
1  | 0.000023   | 0.000014 
1  | 0.000051   | 0.000007 
1  | 0.000009   | 0.000131 

我該怎麼做？

Answer 1

，如果你有相同的ID，那麼你可以嘗試加入：

with a as (
SELECT some_id, avg(exposure_value) monthly_avg_1000,date_trunc('month', measurement_time) d 
FROM mytable 
WHERE pressure_level = 1000 
AND some_id = 7 
GROUP BY some_id, date_trunc('month', measurement_time) 
) 
, b as (
SELECT some_id, avg(exposure_value) monthly_avg_925, date_trunc('month', measurement_time) d 
FROM mytable 
WHERE pressure_level = 925 
AND some_id = 7 
GROUP BY some_id, date_trunc('month', measurement_time) 
) 
select distinct a.some_id, monthly_avg_1000,monthly_avg_925 
from a 
join b on a.some_id = b.some_id and a.d = b.d