按顺序选择列

Question

亲爱的技术我需要你的帮助

我有一张表有2列，一列是Series，第二列是item 像

Series   item
1       apple
2       apple
3       apple
5       apple
6       apple
7       apple
8       apple

我希望以

结果

from    to     item  total
1       3      apple   3
5       8      apple   4

Answer 1

大多数数据库都有一个名为row_number()的函数，可生成序列号。它可以在这种情况下使用。此函数与Series之间的差异对于组来说是不变的：

select min(Series) as "from", max(Series) as "to", item, count(*) as num
from (select t.*, row_number() over (partition by item order by Series) as seqnum
      from table t
     ) t
group by (Series - seqnum), item;