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savadev/sampling_example.sql

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Created October 25, 2024 04:14
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Data sampling in PostgreSQL
Raw
sampling_example.sql
-- sample data and assign new or returning user type
sampledata as (
select a.user_id,
a.created_at
, case
when a.created_at between a.firstdate and a.firstdate+27 then 'new'
else 'returning'
end as type
from (
select user_id
, left(right(user_id, 4), 2) as sample
, created_at
, firstdate::date as first_date
from data
group by 1, 2, 3, 4
) a
where a.sample='04'
group by 1, 2
)
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