sql - 用于从特定行生成列的大查询语法

Question

我整天都在努力解决这个问题，似乎找不到合适的解决方案。我的数据具有以下结构:

dauid       question    total
------------------------------
35200004    8           300.0    
35200004    9           500.0    
35200005    8           400.0    
35200005    9           600.0    
35200006    8           900.0    
35200006    9           1200.0

我想产生以下输出:

dauid       total_8    total_9   normalized_total
----------------------------------------------------
35200004    300.0      500.0     (total_8 / total_9)
35200005    400.0      600.0     
35200006    900.0      1200.0    

我可以在没有标准化总数的情况下生活，但我真的很想找到一种方法，将问题列中的不同组作为每个 dauid 字段的唯一列。我一直在搞乱我发现的各种例子，但似乎无法得到我需要的东西。

编辑:

8和9的值不是固定的，这只是一个例子。每个 dauid 有 450 个对应的问题，表格有几百万行。我需要一种方法能够有选择地查询其中的两行或更多行，然后将每一行构建为一列。

编辑#2:

要添加更多上下文，这是我正在进行的查询类型:

SELECT dauid, question, total, male, female
FROM [canada_census_2011.ontario] 
WHERE csdname CONTAINS 'Toronto'
AND (REGEXP_MATCH(question, r'(^9$)') OR REGEXP_MATCH(question, r'(^8$)') ) 
GROUP BY dauid, question, total, male, female
ORDER BY dauid; 

编辑#3:非常好，感谢 Pentium10，最终查询如下所示:

select dauid,
sum(if(REGEXP_MATCH(question, r'(^8$)'),total,0)) as total_8,
sum(if(REGEXP_MATCH(question, r'(^9$)'),total,0)) as total_9,
sum(if(REGEXP_MATCH(question, r'(^8$)'),total,0))/sum(if(REGEXP_MATCH(question, r'(^9$)'),total,0)) as normalized
FROM [canada_census_2011.ontario] 
WHERE csdname CONTAINS 'Toronto'
AND (REGEXP_MATCH(question, r'(^9$)') OR REGEXP_MATCH(question, r'(^8$)') )
GROUP BY dauid

Answer 1

此示例查询生成您想要的内容

select dauid,
sum(if(question=8,total,0)) as total_8,
sum(if(question=9,total,0)) as total_9,
sum(if(question=8,total,0))/sum(if(question=9,total,0)) as normalized
 from
(select 35200004 as dauid,  8 as question,           300.0     as total),
(select 35200004 as dauid,  9 as question,           500.0     as total),
(select 35200005 as dauid,  8 as question,           400.0     as total),
(select 35200005 as dauid,  9 as question,           600.0     as total),
(select 35200006 as dauid,  8 as question,           900.0     as total),
(select 35200006 as dauid,  9 as question,           1200.0 as total)
group by dauid

返回

+---+----------+---------+---------+--------------------+---+
|   |  dauid   | total_8 | total_9 |     normalized     |   |
+---+----------+---------+---------+--------------------+---+
| 1 | 35200004 | 300.0   | 500.0   | 0.6                |   |
| 2 | 35200005 | 400.0   | 600.0   | 0.6666666666666666 |   |
| 3 | 35200006 | 900.0   | 1200.0  | 0.75               |   |
+---+----------+---------+---------+--------------------+---+