如何将 sql 中的行按特定顺序分组

Question

假设我有一个有 3 列的 table

one	two	three
x	LF	1
x	FI	2
x	LF	3
x	FI	4
x	FI	5
x	FI	6
x	LF	7
x	FI	8
x	LF	9
x	FI	10
x	LF	11
x	LF	12
x	LF	13
x	LF	14
x	FI	15

现在我想要的是将 'two' 列分组并取最低的 'third' 列值，这将给我输出

one	two	three
x	LF	1
x	FI	2
x	LF	3
x	FI	4
x	LF	7
x	FI	8
x	LF	9
x	FI	10
x	LF	11
x	FI	15

我怎样才能做到这一点？

Answer 1

您似乎想要更改的行。您可以使用 lag():

select one, two, three
from (select t.*,
             lag(two) over (order by three) as prev_two
      from t
     ) t
where prev_two is null or prev_two <> two;