是否有办法从所有各行中减去首选行的价值? 因此,我
t = 1, v = 500
t = 2, v = 800
t = 3, v = 1200
我会这样做。
t = 1, v = 0
t = 2, v = 300
t = 3, v = 700
I m always looking for a portable solution but a Postgres solution works just the same :-) Thank you.
SELECT v - FIRST_VALUE(v) OVER (ORDER BY t)
FROM mytable
ORDER BY
t
可能这样做
SELECT mt2.t, mt2.v - mt1.v AS v
FROM MyTable mt1
CROSS JOIN MyTable mt2
WHERE mt1.t = 1
大部分不使用窗口功能的便携方式:
select v - first
from
mytable,
(select v as first from mytable order by t limit 1) as inner
order by t
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