变换 NULL 把它们串起来 'NULL' ，空到 NULL 使用 coalesce ，然后转换回。像这样：

create temporary macro empty2null(s string)
case when s='' then null
     when s is null then 'NULL'
     else s
  end;

create temporary macro NULL2empty (s string)
case when s='NULL' then null
     when s is null then ''
     else s
end;

select NULL2empty(coalesce(empty2null(''),empty2null(5)));

唯一不方便的是，您必须将每一列都 Package 到 empty2null() ，除了常量 5 ，只是检查一下
测验：

hive> create temporary macro empty2null(s string)
    > case when s='' then null
    >      when s is null then 'NULL'
    >      else s
    >   end;
OK
Time taken: 0.97 seconds
hive>
    > create temporary macro NULL2empty (s string)
    > case when s='NULL' then null
    >      when s is null then ''
    >      else s
    > end;
OK
Time taken: 0.02 seconds
hive>
    > select NULL2empty(coalesce(empty2null(''),empty2null(5)));
OK
5
Time taken: 7.08 seconds, Fetched: 1 row(s)
hive> select NULL2empty(coalesce(empty2null(''),empty2null('')));
OK

Time taken: 3.96 seconds, Fetched: 1 row(s)
hive> select NULL2empty(coalesce(empty2null(''),empty2null(null)));
OK
NULL
Time taken: 0.952 seconds, Fetched: 1 row(s)
hive> select NULL2empty(coalesce(empty2null(5),empty2null('')));
OK
5
Time taken: 0.067 seconds, Fetched: 1 row(s)