问题描述
org.postgresql.util.PsqlException: ERROR: Syntax error at or near "JOIN"
Position: 550
GROUP BY year
JOIN temp ON temp.year = MN.ye
^
-- INNER JOIN (
这是我的查询
WITH temp as(
SELECT
SUM(CASE WHEN rain = 'TRUE' THEN 1 END)*1.0/COUNT(date) * 100 as rain,EXTRACT(YEAR FROM date) as year
FROM sample
GROUP BY year
)
SELECT AVG(mind) as avg_min,AVG(maxd) as avg_max,EXTRACT(YEAR FROM date) as year
FROM sample MN
GROUP BY year
JOIN temp ON temp.year = MN.year
和我的数据样本
date prcp maxd mind rain
1948-01-01 00:00:00 0.47 51 42 TRUE
1948-01-02 00:00:00 0.59 45 36 TRUE
1948-01-03 00:00:00 0.42 45 35 TRUE
1948-01-04 00:00:00 0.31 45 34 TRUE
1948-01-05 00:00:00 0.17 45 32 TRUE
1948-01-06 00:00:00 0.44 48 39 TRUE
1948-01-07 00:00:00 0.41 50 40 TRUE
1948-01-08 00:00:00 0.04 48 35 TRUE
1948-01-09 00:00:00 0.12 50 31 TRUE
1948-01-10 00:00:00 0.74 43 34 TRUE
1948-01-11 00:00:00 0.01 42 32 TRUE
1948-01-12 00:00:00 0 41 26 FALSE
1948-01-13 00:00:00 0 45 29 FALSE
1948-01-14 00:00:00 0 38 26 FALSE
1948-01-15 00:00:00 0 34 31 FALSE
1948-01-16 00:00:00 0 34 28 FALSE
1948-01-17 00:00:00 0 35 29 FALSE
1948-01-18 00:00:00 0 33 28 FALSE
1948-01-19 00:00:00 0 34 27 FALSE
1948-01-20 00:00:00 0 36 29 FALSE
1948-01-21 00:00:00 0 48 32 FALSE
1948-01-22 00:00:00 0.21 47 44 TRUE
1948-01-23 00:00:00 0 47 43 FALSE
1948-01-24 00:00:00 0.1 45 34 TRUE
1948-01-25 00:00:00 0 46 30 FALSE
1948-01-26 00:00:00 0 45 32 FALSE
1948-01-27 00:00:00 0 53 33 FALSE
1948-01-28 00:00:00 0 53 25 FALSE
1948-01-29 00:00:00 0.22 42 34 TRUE
1948-01-30 00:00:00 0.03 47 30 TRUE
1948-01-31 00:00:00 0.21 35 27 TRUE
我理想的结果将是类似于此的
avg_tmin,avg_tmax,avg_rain,year
x x x 1948
x x x 1949
...
所以我的数据集中每年的平均头脑（tmin），maxd（tmax）和降雨
解决方法
我不了解您的查询尝试实现的逻辑。但是，从样本数据和预期结果来看，您似乎只想聚合：
select
avg(mind) avg_mind,avg(maxd) avg_maxd,avg( (rain)::int ) avg_rain,extract(year from date) year
from sample
group by extract(year from date)
我不认为需要JOIN开头：
SELECT count(*) filter (where rain = 'TRUE') * 1.0 / count(*) as rain,AVG(mind) as avg_min,AVG(maxd) as avg_max,EXTRACT(YEAR FROM date) as year
FROM sample
GROUP BY year
以上是完成所需工作的最有效方法。
但是，要回答您的直接问题，为什么代码不起作用：您需要在联接后移动组，并且不能在同一级别上使用列别名year（{{1 }}）的定义位置：
mn请注意，这不使用CTE中的WITH temp as (
SELECT count(*) filter (where rain = 'TRUE') *1.0 / COUNT(date) * 100 as rain,EXTRACT(YEAR FROM date) as year
FROM sample
GROUP BY year
),SELECT AVG(mn.mind) as avg_min,AVG(mn.maxd) as avg_max,tmp.year
FROM sample MN
JOIN temp ON temp.year = EXTRACT(YEAR FROM mn.date)
GROUP BY tmp.year
列。如果要添加，则需要通过以下方式将其添加到组中：
rain或将其拆分为两个合并的聚合查询。
WITH temp as (
SELECT count(*) filter (where rain = 'TRUE') *1.0 / COUNT(date) * 100 as rain,tmp.year,tmp.rain
FROM sample MN
JOIN temp ON temp.year = EXTRACT(YEAR FROM mn.date)
GROUP BY tmp.year,tmp.rain
但再次：不需要联接，这会使整个过程效率降低。