Question

我试图从bigquery中的给定日期获取1年前的数据。 date(DATE_ADD(date(DATE_ADD(timestamp(New_date),(DATEDIFF(timestamp(New_date), CURRENT_DATE())-1), "DAY")), -354, "DAY"))

上面的查询有效，但是当我尝试将它放在case语句中时，我得到null。

sum(case when date(New_day) = date(DATE_ADD(date(DATE_ADD(timestamp(New_date),(DATEDIFF(timestamp(New_date), CURRENT_DATE())-1), "DAY")), -354, "DAY")) then 'this is working' else null end) as lastyeardata

如何在同一天获取1年前的数据进行同比较？

编辑@米哈伊尔的建议： #standardSQl WITH `yourTable` AS ( SELECT 1 AS id, '2017-08-14' AS New_date, '1234' AS volume UNION ALL SELECT 2 AS id, '2017-08-13' AS New_date, '2345' AS volume UNION ALL SELECT 3 AS id, '2017-08-14' AS New_date, '3456' AS volume UNION ALL SELECT 4 AS id, '2017-08-14' AS New_date, '4567' AS volume UNION ALL SELECT 5 AS id, '2016-08-14' AS New_date, '5678' AS volume UNION ALL SELECT 6 AS id, '2016-08-13' AS New_date, '6789' AS volume UNION ALL SELECT 7 AS id, '2016-08-12' AS New_date, '6789' AS volume UNION ALL SELECT 8 AS id, '2016-08-11' AS New_date, '1011' AS volume ) select New_date ,volume as thisyeardata ,Case WHEN PARSE_DATE('%Y-%m-%d', New_date) = DATE_ADD(PARSE_DATE('%Y-%m-%d', New_date), INTERVAL -1 YEAR) THEN volume ELSE NULL end as lastyearvolume ,DATE_ADD(PARSE_DATE('%Y-%m-%d', New_date), INTERVAL -1 YEAR) as lastyear FROM `yourTable`

由于某些原因，lastyearvolume给了我null。

Answer 1

下面是BigQuery Standard SQL（BigQuery团队真正推荐使用它与Legacy一个）

#standardSQl
WITH `yourTable` AS (
  SELECT 1 AS id, '2017-08-14' AS New_date, '2016-08-14' AS New_day UNION ALL
  SELECT 2 AS id, '2017-08-13' AS New_date, '2016-08-13' AS New_day UNION ALL
  SELECT 3 AS id, '2017-08-14' AS New_date, '2016-08-12' AS New_day UNION ALL
  SELECT 4 AS id, '2017-08-14' AS New_date, '2016-08-11' AS New_day 

)
SELECT 
  COUNT(
    CASE 
      WHEN PARSE_DATE('%Y-%m-%d', New_day) = DATE_ADD(PARSE_DATE('%Y-%m-%d', New_date), INTERVAL -1 YEAR) 
      THEN 'this is working' 
      ELSE NULL 
    END
  ) AS lastyeardata
FROM `yourTable`

正如您所期望的那样，只计算两行，因为它们分别为New_date和New_day年，其余行不是

上面的示例假设您的日期字段属于STRING类型如果它们是日期类型 - 您只需省略PARSE_DATE函数

DATE_ADD有对应的 - DATE_SUB - 所以它可以用作DATE_SUB(PARSE_DATE('%Y-%m-%d', New_date), INTERVAL 1 YEAR)

根据您更新的示例进行更新：

简单快捷的调整查询工作方式：

#standardSQl
WITH `yourTable` AS (
SELECT 1 AS id, '2017-08-13' AS New_date, '1234' AS volume UNION ALL
SELECT 2 AS id, '2017-08-14' AS New_date, '2345' AS volume UNION ALL
SELECT 3 AS id, '2017-08-15' AS New_date, '3456' AS volume UNION ALL
SELECT 4 AS id, '2017-08-16' AS New_date, '4567' AS volume UNION ALL
SELECT 5 AS id, '2016-08-13' AS New_date, '5678' AS volume UNION ALL
SELECT 6 AS id, '2016-08-14' AS New_date, '6789' AS volume UNION ALL
SELECT 7 AS id, '2016-08-15' AS New_date, '6789' AS volume UNION ALL
SELECT 8 AS id, '2016-08-16' AS New_date, '1011' AS volume
)
SELECT 
  this_year.New_date
  ,this_year.volume AS thisyeardata
  ,last_year.volume AS lastyeardata
FROM `yourTable` AS this_year
JOIN `yourTable` AS last_year
ON PARSE_DATE('%Y-%m-%d', last_year.New_date) = DATE_ADD(PARSE_DATE('%Y-%m-%d', this_year.New_date), INTERVAL -1 YEAR)

获取去年的数据

1 个答案: