--Dataset Name: Jobs
week date job_id
----------------------
wk1 01/15 300
wk1 01/15 301
wk1 01/15 302
wk2 01/22 300
wk2 01/22 302
wk2 01/22 303
wk2 01/22 304
wk3 01/29 302
wk3 01/29 304
wk3 01/29 305
我有一个像上面的数据集。我想创建3个其他列:
is_job_id_present_in_wk1
is_job_id_present_in_wk2
is_job_id_present_in_wk3
我想编写一个SQL查询,将三个新列的每一行标记为1或0。我不想使用自我加入。我想利用一些分析窗口函数。
例如,对于给定数据集中的第一行,is_job_id_present_in_wk1,is_job_id_present_in_wk2和is_job_id_present_in_wk3的值将为1(因为在所有三个星期中都存在job_id 300)。
对于给定数据集中的第二行,is_job_id_present_in_wk1的值为1,is_job_id_present_in_wk2的值为0,is_job_id_present_in_wk3的值为0(因为job_id 301仅在整个第1周都存在)。
尝试到现在为止:
SELECT week, date, job_id
, CASE WHEN job_id =
FIRST_VALUE(CASE WHEN week='wk1' THEN job_id ELSE NULL END) OVER(ORDER BY job_id rows between current row and current row)
THEN 1 ELSE 0 END as is_job_id_present_in_wk1
FROM jobs;
尝试:
SELECT week, date, job_id,
max( case when week = 'wk1' then 1 else 0 end )
over (partition by job_id) as is_job_id_present_in_wk1,
max( case when week = 'wk2' then 1 else 0 end )
over (partition by job_id) as is_job_id_present_in_wk2,
max( case when week = 'wk3' then 1 else 0 end )
over (partition by job_id) as is_job_id_present_in_wk2
FROM jobs;
也尝试以下版本:
SELECT week, date, job_id
, CASE WHEN EXISTS( SELECT 1 FROM jobs job1
WHERE job1.job_id = jobs.job_id AND job1.week = 'wk1' )
THEN 1 ELSE 0 END as is_job_id_present_in_wk1
, CASE WHEN EXISTS( SELECT 1 FROM jobs job1
WHERE job1.job_id = jobs.job_id AND job1.week = 'wk2' )
THEN 1 ELSE 0 END as is_job_id_present_in_wk2
, CASE WHEN EXISTS( SELECT 1 FROM jobs job1
WHERE job1.job_id = jobs.job_id AND job1.week = 'wk3' )
THEN 1 ELSE 0 END as is_job_id_present_in_wk3
FROM jobs;
因为它可能比带有分析功能的版本更快,尤其是在job_id + week列上创建复合索引时。
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