Question

在Google BigQuery中，我想并排显示两个不同日期的数据。我想显示今天的数据，然后是七天前的数据进行比较。我的FROM子句选择一系列表，每个表对应一个日期。

SELECT
  DATE(TIMESTAMP(INTEGER(visitStartTime*1000000))) AS GMT_Date,
  DAYOFWEEK(TIMESTAMP(INTEGER(visitStartTime*1000000))) AS GMT_Weekday,
  IF(hits.customDimensions.index=15, hits.customDimensions.value, NULL) AS apikey,
  hits.eventInfo.eventCategory AS event_category,
  SUM(totals.visits) AS visit_count,


  DATE(DATE_ADD(TIMESTAMP(INTEGER(visitStartTime*1000000)),-7,"DAY")) AS test,
 // HERE I need to show SUM(totals.visits) but for the date of 'test' above

FROM (TABLE_DATE_RANGE([100610078.ga_sessions_], TIMESTAMP('20150529'),TIMESTAMP('20150711')))
WHERE
  IF(hits.customDimensions.index=15, hits.customDimensions.value, NULL) IS NOT NULL
GROUP BY
  GMT_Date,
  GMT_Weekday,
  event_category,
  test,
  apikey
ORDER BY
  GMT_Date DESC,
  visit_count DESC
LIMIT
  30

在＆＃39;测试＆＃39;之后，我想显示测试日期的访问总和。我该怎么做？我在BigQuery语法页面上看不到任何与此相似的内容。

以下是其目前正在返回的图片：http://prntscr.com/7s8w58

在＆＃39;测试＆＃39;我希望像previous_week_visits这样的列与visit_count具有相同的数据但是需要测试日期。

Answer 1

一种方法是使用窗口函数。您可以使用带固定基数的DATEDIFF将DATE映射到连续的INTEGER，然后使用LAG函数查找值，以下查询显示了此方法的示例：

select 
  d,
  value,
  lag(d, 3) over (order by diff) prev_d,
  lag(value, 3) over (order by diff) prev_value
from (
select d, datediff(d, date('1970-01-01')) diff, value from
(select date('2012-01-01') d, 'a' value),
(select date('2012-01-02') d, 'b' value),
(select date('2012-01-03') d, 'c' value),
(select date('2012-01-04') d, 'd' value),
(select date('2012-01-05') d, 'e' value),
(select date('2012-01-06') d, 'f' value),
(select date('2012-01-07') d, 'g' value),
(select date('2012-01-08') d, 'h' value),
(select date('2012-01-09') d, 'i' value),
(select date('2012-01-10') d, 'j' value)
)

结果是：

Row d           value   prev_d      prev_value   
1   2012-01-01  a       null        null     
2   2012-01-02  b       null        null     
3   2012-01-03  c       null        null     
4   2012-01-04  d       2012-01-01  a    
5   2012-01-05  e       2012-01-02  b    
6   2012-01-06  f       2012-01-03  c    
7   2012-01-07  g       2012-01-04  d    
8   2012-01-08  h       2012-01-05  e    
9   2012-01-09  i       2012-01-06  f    
10  2012-01-10  j       2012-01-07  g

在列中显示两个不同日期的数据

1 个答案: