全外连接行为

Question

HIVE SQL - 我有 2 个表。 survey 和survey_cmets 结构如下：

create external table if not exists survey(
id string,
category_name string, 
subcategory_name string)
STORED AS parquet;

insert into survey(id, category_name, subcategory_name) 
values ('1', 'Engine', 'Engine problem other than listed');
insert into survey(id, category_name, subcategory_name) 
values ('1', 'Exterior Body', 'Color match of painted parts');
insert into survey(id, category_name, subcategory_name) 
values ('1', 'Exterior Body', 'Tail lights');
insert into survey(id, category_name, subcategory_name) 
values ('1', 'Heating/Ventilation and Cooling', 'Front windshield fogs up');
insert into survey(id, category_name, subcategory_name) 
values ('1', 'Transmission', 'Rough shifting');

create external table if not exists survey_comments(
id string,
category_name_txt string, 
subcategory_name_txt string,
comments string)
STORED AS parquet;

insert into survey_comments(id, category_name_txt, subcategory_name_txt) 
values ('1', 'Exterior Body', 'Tail lights', 'Moisture in lower portion of rear tail lights along with leaves etc.');
insert into survey_comments(id, category_name_txt, subcategory_name_txt) 
values ('1', 'Heating/Ventilation and Cooling', 'Front windshield fogs up', 'Small amount of fog low on front windshield during/after rain.');
insert into survey_comments(id, category_name_txt, subcategory_name_txt) 
values ('1', 'Miscellaneous', 'General problem other than listed', 'When filling vehicle with gas; the pumps fill the gas line too quickly, had to hold the pump handle only 1/2 way on.');
insert into survey_comments(id, category_name_txt, subcategory_name_txt) 
values ('1', 'Miscellaneous', 'General problem other than listed', 'Touch-up paint too red, not same red as on the car.');

现在我的完整外连接如下所示：

select b.id, b.category_name, b.subcategory_name, a.category_name_txt, a.sub_category_name_txt, a.comments
from   survey b full outer join survey_comments a 
on (
b.id = a.id and              
b.category_name     = a.category_name_txt and                      b.subcategory_name  = a.sub_category_name_txt
)

我没有得到survey_comment_txt 中category_name 为“Miscellaneous”的行。我需要在调查和survey_cmets 中不匹配的行作为单独的行和匹配的行。我做错了什么。

Answer 1

使用 CTE 进行测试，发现了两个问题。 1st：您在survey_cmets 中插入了四列，但只命名了三列。 第二个：在查询列名中应该是subcategory_name_txt，而不是sub_category_name_txt。

修复后测试：

with survey as (
select stack(5,
'1', 'Engine', 'Engine problem other than listed',
'1', 'Exterior Body', 'Color match of painted parts',
'1', 'Exterior Body', 'Tail lights',
'1', 'Heating/Ventilation and Cooling', 'Front windshield fogs up',
'1', 'Transmission', 'Rough shifting') as (id, category_name, subcategory_name) 
),

survey_comments as (
select stack(4,

'1', 'Exterior Body', 'Tail lights', 'Moisture in lower portion of rear tail lights along with leaves etc.',
'1', 'Heating/Ventilation and Cooling', 'Front windshield fogs up', 'Small amount of fog low on front windshield during/after rain.',
'1', 'Miscellaneous', 'General problem other than listed', 'When filling vehicle with gas; the pumps fill the gas line too quickly, had to hold the pump handle only 1/2 way on.',
'1', 'Miscellaneous', 'General problem other than listed', 'Touch-up paint too red, not same red as on the car.') as (id, category_name_txt, subcategory_name_txt,comments)
)

select b.id, b.category_name, b.subcategory_name, a.category_name_txt, a.subcategory_name_txt, a.comments
from   survey b full outer join survey_comments a 
on (
b.id = a.id and              
b.category_name     = a.category_name_txt and b.subcategory_name  = a.subcategory_name_txt
)

返回：

b.id    b.category_name b.subcategory_name  a.category_name_txt a.subcategory_name_txt  a.comments  
1   Engine  Engine problem other than listed    NULL    NULL    NULL    
1   Exterior Body   Color match of painted parts    NULL    NULL    NULL    
1   Exterior Body   Tail lights Exterior Body   Tail lights Moisture in lower portion of rear tail lights along with leaves etc.    
1   Heating/Ventilation and Cooling Front windshield fogs up    Heating/Ventilation and Cooling Front windshield fogs up    Small amount of fog low on front windshield during/after rain.  
NULL    NULL    NULL    Miscellaneous   General problem other than listed   Touch-up paint too red, not same red as on the car. 
NULL    NULL    NULL    Miscellaneous   General problem other than listed   When filling vehicle with gas; the pumps fill the gas line too quickly, had to hold the pump handle only 1/2 way on.    
1   Transmission    Rough shifting  NULL    NULL    NULL    

Miscellaneous 被返回。