如何根据另一列对一列求和？

Question

下面有这段代码，我想在 notification_date 按日期分组时对 num 列求和？我还想将 num 列改为 DESC 这可能吗？

from pyspark.sql.functions import col,desc

results = spark.sql("SELECT lhd_2010_name, lhd_2010_code, notification_date, num FROM cases_df")    
    
results.show()
spark.stop()

Answer 1

从 Spark 语法来看它看起来不错，您必须按如下方式修改 SQL 查询：

如果您只需要总和和日期列：

select * from 
( select notification_date,sum(num) as s_num 
  from cases_d 
  group by notification_date ) a 
order by s_num desc

如果需要所有字段：

select b.lhd_2010_name,b.lhd_2010_code,a.notification_date,a.s_num 
from (select notification_date,sum(num) as s_num 
      from cases_d 
      group by notification_date) a 
join cases_d b
on a.notification_date=b.notification_date
order by s_num desc

如何根据另一列对一列求和？

How so sum a column based on another column?

pyspark

apache-spark-sql