我正在使用Teradata解决抽样问题
以下是数据格式
ID Group Rank
1 dog 1
1 cat 1
1 lion 1
1 elephant 2
2 dog 1
2 cat 1
2 lion 1
2 elephant 1
3 dog 1
3 cat 2
3 lion 1
3 elephant 1
4 dog 2
4 cat 1
4 lion 1
4 elephant 1
...
理想情况下，我想为组中的每个条目返回一个样本号，但ID中的值必须唯一。
以下是我产生的当前查询，但这返回ID的重复项
SELECT ID, Group FROM Table
WHERE rank = 1
SAMPLE
WHEN group = 'dog' then 10
WHEN group = 'cat' then 10
WHEN group = 'elephant' then 5
WHEN group = 'lion' then 5
END
with cte as
(
SELECT ID, Group,
random(1,10000) as rnd -- RANDOM can't be directly used in OLAP-functions
FROM Table
WHERE rank = 1
)
SELECT ID, Group
FROM cte
QUALIFY
ROW_NUMBER() -- get one random row per ID
OVER (PARTITION BY ID
ORDER BY rnd) = 1
SAMPLE
WHEN group = 'dog' then 10
WHEN group = 'cat' then 10
WHEN group = 'elephant' then 5
WHEN group = 'lion' then 5
END
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