在大查询中重建从长到长(标准SQL)

Question

不幸的是,在BQ中重塑它并不像在R中那么容易,我无法导出这个项目的数据.

这是输入

date    country A             B         C      D
20170928    CH  3000.3        121       13     3200
20170929    CH  2800.31       137       23     1614.31

预期产出

date    country Metric  Value  
20170928    CH  A       3000.3  
20170928    CH  B       121     
20170928    CH  C       13     
20170928    CH  D       3200
20170929    CH  A       2800.31 
20170929    CH  B       137       
20170929    CH  C       23     
20170929    CH  D       1614.31

我的表还有更多的列和行(但我假设需要很多手册)

Answer 1

以下是适用于BigQuery标准SQL的内容，不需要重复选择，具体取决于列数。它会选择您所拥有的数量并将其转换为指标和值

#standardSQL
SELECT DATE, country,
  metric, SAFE_CAST(value AS FLOAT64) value
FROM (
  SELECT DATE, country, 
    REGEXP_REPLACE(SPLIT(pair, ':')[OFFSET(0)], r'^"|"$', '') metric, 
    REGEXP_REPLACE(SPLIT(pair, ':')[OFFSET(1)], r'^"|"$', '') value 
  FROM `project.dataset.yourtable` t, 
  UNNEST(SPLIT(REGEXP_REPLACE(to_json_string(t), r'{|}', ''))) pair
)
WHERE NOT LOWER(metric) IN ('date', 'country')

您可以使用虚拟数据在上面的问题中进行测试/操作

#standardSQL
WITH `project.dataset.yourtable` AS (
  SELECT '20170928' DATE, 'CH' country, 3000.3 A, 121 B, 13 C, 3200 D UNION ALL
  SELECT '20170929', 'CH', 2800.31, 137, 23, 1614.31
)
SELECT DATE, country,
  metric, SAFE_CAST(value AS FLOAT64) value
FROM (
  SELECT DATE, country, 
    REGEXP_REPLACE(SPLIT(pair, ':')[OFFSET(0)], r'^"|"$', '') metric, 
    REGEXP_REPLACE(SPLIT(pair, ':')[OFFSET(1)], r'^"|"$', '') value 
  FROM `project.dataset.yourtable` t, 
  UNNEST(SPLIT(REGEXP_REPLACE(to_json_string(t), r'{|}', ''))) pair
)
WHERE NOT LOWER(metric) IN ('date', 'country')

结果如预期

DATE        country metric  value    
20170928    CH      A       3000.3   
20170928    CH      B       121.0    
20170928    CH      C       13.0     
20170928    CH      D       3200.0   
20170929    CH      A       2800.31  
20170929    CH      B       137.0    
20170929    CH      C       23.0     
20170929    CH      D       1614.31