如何将多个选择结果合并到一个表中？

Question

我有一个查询，从同一个表中返回的月平均值，但对于不同的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) 

然后我有相同的查询，但对于不同的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) 

两个查询返回12行（每月1）与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 

我想结合这两个查询，所以吨帽子的monthly_avg_ *列都出现在决赛桌上：

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

我该怎么做？

Answer 1

，如果你有相同的ID，那么你可以尝试加入：

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