Hive，SQL：为Hive表中的100多列中的每一列返回COUNT个NULL值

Question

什么是为Hive表中的100多列中的每一列返回COUNT个NULL值的SQL代码？

Answer 1

在SQL中它将是

 SELECT 
   SUM(CASE WHEN a is null then 1 else 0 end) as a_null_count,
   SUM(CASE WHEN b is null then 1 else 0 end) as b_null_count,       
   --- ...
   SUM(CASE WHEN z is null then 1 else 0 end) as z_null_count
 FROM table