Oracle SQL查询对连续记录进行分组

我已将电子表格中的数据(金额"和叙述")导入表中，并且需要查询的帮助，以便根据连续记录的叙述"对它们进行分组，例如:

I've imported data ("Amount" and "Narration") from a spreadsheet into a table and need help with a query to group consecutive records according to their "Narration", for example:

预期输出:

line_no  amount   narration   calc_group <-Not part of table
----------------------------------------
1          10      Reason 1       1
2         -10      Reason 1       1
3           5      Reason 2       2
4           5      Reason 2       2
5         -10      Reason 2       2
6          -8      Reason 1       3
7           8      Reason 1       3
8          11      Reason 1       3
9          99      Reason 3       4
10        -99      Reason 3       4

我已经尝试了一些分析功能:

I've tried some analytical functions:

select   line_no, amount, narration,
         first_value (line_no) over 
         (partition by narration order by line_no) "calc_group"
from     test
order by line_no

但这不起作用，因为第6至8行的旁白与第1行和第2行相同.

But that does not work because the Narration of line 6 to 8 is the same as line 1 and 2.

line_no  amount   narration   calc_group
----------------------------------------
1          10      Reason 1       1
2         -10      Reason 1       1
3           5      Reason 2       3
4           5      Reason 2       3
5         -10      Reason 2       3
6          -8      Reason 1       1
7           8      Reason 1       1
8          11      Reason 1       1
9          99      Reason 3       4
10        -99      Reason 3       4

更新

我已经设法使用滞后分析功能和序列来做到这一点，虽然不是很优雅，但是它可以工作.应该有更好的方法，请发表评论！

UPDATE

I've managed to do it using lag analytical function and sequences, not very elegant but it works. There should be a better way, please comment!

create or replace function get_next_test_seq
   return number
as
begin
   return test_seq.nextval;
end get_next_test_seq;

create or replace function get_curr_test_seq
   return number
as
begin
   return test_seq.currval;
end get_curr_test_seq;

update test
set    group_no =
          (with cte1
                as (select   line_no, amount, narration,
                             lag (narration) over (order by line_no) prev_narration, group_no
                    from     test
                    order by line_no),
                cte2
                as (select line_no, amount, narration, group_no,
                           case when prev_narration is null or prev_narration <> narration then get_next_test_seq else get_curr_test_seq end new_group_no
                    from   cte1)
           select new_group_no
           from   cte2
           where  cte2.line_no = test.line_no);

更新2

我对更好的答案感到满意.谢谢kordiko！

UPDATE 2

I'm satisfied with the better accepted answer. Thanks kordiko!