Question

我有一个包含列号的

表

Numbers
------
3
5

我正试图获得那些因素。我使用以下逻辑但没有正确的结果

Select 
    Numbers
    ,EXP(SUM(LN(Numbers)) OVER (ORDER BY Numbers)) Factorial 
FROM testTbl

* 输出 *

Numbers Factorial
------  ---------
3   3.00000000000000000000000000000000000001
5   15.0000000000000000000000000000000000002

有什么问题？请帮忙

Expected
--------

Numbers Factorial
------  ---------
3   6
5   120

提前致谢

Answer 1

如果是我，我会创建一个阶乘函数并在我的查询中调用该用户定义的函数。像

这样的东西

SQL> create function factorial( p_n in number )
  2    return number
  3  is
  4  begin
  5    if( p_n = 1 )
  6    then
  7      return p_n;
  8    else
  9      return p_n * factorial( p_n - 1 );
 10    end if;
 11  end;
 12  /

Function created.

SQL> with t as (
  2    select 3 num from dual
  3    union all
  4    select 5 from dual
  5  )
  6  select num,
  7         factorial(num)
  8    from t;

       NUM FACTORIAL(NUM)
---------- --------------
         3              6
         5            120

如果由于某种原因您无法定义新功能并且您确实希望在SQL中执行此功能，则可以生成小于表中数字的所有数字，然后汇总这些生成的数字。

SQL> ed
Wrote file afiedt.buf

  1  with t as (
  2    select 3 num from dual
  3    union all
  4    select 5 from dual
  5  )
  6  select t.num,
  7         exp( sum(ln(gen.num))) factorial
  8    from (select level num
  9            from dual
 10         connect by level <= (select max(t.num) from t)) gen,
 11         t
 12   where gen.num <= t.num
 13*  group by t.num
SQL> /

       NUM  FACTORIAL
---------- ----------
         5        120
         3          6

Answer 2

我从另一个角度开始，尝试在SQL语句中完成所有操作（使用表testTbl和列号）。

这就是我想出来的，看看它是否适合你：

  SELECT testtbl.numbers,
         ROUND( EXP( SUM( LN( t1.n ) ) ) ) AS factorial
    FROM (    SELECT UNIQUE LEVEL n
                FROM testtbl
          CONNECT BY LEVEL <= numbers) t1,
         (    SELECT UNIQUE LEVEL n
                FROM testtbl
          CONNECT BY LEVEL <= numbers) t2,
         testTbl
   WHERE t1.n <= t2.n
     AND t2.n = testTbl.numbers
   GROUP BY testtbl.numbers
   ORDER BY testtbl.numbers;

给出输出：

Numbers Factorial
3       6  
5       120

希望它有所帮助...

在Oracle中查找factorial

2 个答案: