@ashishsingh答案演示
Hive

create table mytable (i int,j int,k int);
insert into mytable values (1,2,null),(null,5,null),(7,null,9);

select * from mytable
;

+-----------+-----------+-----------+
| mytable.i | mytable.j | mytable.k |
+-----------+-----------+-----------+
| 1         | 2         | NULL      |
| NULL      | 5         | NULL      |
| 7         | NULL      | 9         |
+-----------+-----------+-----------+

insert overwrite local directory "/tmp/mytable" 
row format delimited fields terminated by "," null defined as '' 
select * from mytable
;

猛击

cat /tmp/mytable/*
1,2,
,5,
7,,9

是的，我需要零钱。您总是查询返回 null 结果如此直接 " " (empty string) 归档。

select if(str is null, " ", str) str from mytable where str is null

使用this:-

INSERT OVERWRITE LOCAL DIRECTORY "/path/to/dir" 
ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t" NULL DEFINED AS '' 
select str from mytable where str is null;

您可以删除 FIELDS TERMINATED BY "\t" 如果不需要

好吧，你总是可以使用case语句，比如：

SELECT CASE WHEN str is null then '' ELSE str END;

请记住，可以使用以下表属性更改处理空字段的方式：
“序列化.null.format”