''''4'''' || (&1 - j)
新值 15: (i - 1) || ''''4'''' || (5 - j)
原值 17: from (select level as i from dual connect by level <= &1) a,
新值 17: from (select level as i from dual connect by level <= 5) a,
原值 18: (select level as j from dual connect by level <= &1) b
新值 18: (select level as j from dual connect by level <= 5) b
STR
--------------------------------------------------------------------------------------------
1 16 15 14 13
2 17 24 23 12
3 18 25 22 11
4 19 20 21 10
5 6 7 8 9
SQL>--------------------------------------------------------------------------------
使用前, 给声明m和n并赋值
代码:--------------------------------------------------------------------------------
var n number;
var m number;
exec :n := &n; :m=&m;
with t as (
select :n as n, :m as m from dual
)
select replace(max(sys_connect_by_path(rank, '''','''')), '''','''') str
from (select i, j, to_char(rank() over(order by tag), ''''999999'''') as rank
from (select i,
j,
-- 顺时针螺旋特征码 clockwise
case least(i - 1, m - j, n - i, j - 1)
when i - 1 then
to_char(i - 1, ''''fm0000'''') || ''''1'''' ||
to_char(j - 1, ''''fm0000'''')
when m - j then
to_char(m - j, ''''fm0000'''') || ''''2'''' ||
to_char(i - 1, ''''fm0000'''')
when n - i then
to_char(n - i, ''''fm0000'''') || ''''3'''' ||
to_char(m - j, ''''fm0000'''')
when j - 1 then
to_char(j - 1, ''''fm0000'''') || ''''4'''' ||
to_char(n - i, ''''fm0000'''')
end as tag
from (select n, level as i from t connect by level <= n) a,
(select m, level as j from t connect by level <= m) b))
start with j = 1
connect by j - 1 = prior j and i = prior i
group by i
-----------------------------------------------------------------------------------------------
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