Any function generating a random number ?

Question

Is there any function which yields a random number every time from a given list of numbers ?
e.g.
Consider table t as :
invoice_no
123
456
789
654
321
987
I want a function executed manually yielding a random invoice no.
How can i achieve ?
Regards
Capri !!!

Answer 1

Cannot reproduce. There must be some misunderstanding.
The selected invoices are just numbered and the required number of random positions is extracted.
Don't know how a valid position can contain a nonexisting invoice number as (valid I presume) invoice numbers were selected before being numbered.
I think the first version was a little unfair: The last invoice couldn't be extracted as dbms_random.value(low,high) can return low but cannot return high.
select invoice_no
  from (select invoice_no,row_number() over (order by null) the_row
          from invoices
         where <your criteria here>
where the_row in (select trunc(dbms_random.value(1,(select count(*) + 1 from invoices)),0)
                     from dual
                    connect by level <= :how_many_to_draw
                  )Regards
Etbin
In my solution I overlooked the possibility that the same invoice could be extracted more than once. So better to follow Dave's suggestion and choose MichaelS's solution
with
invoices as
(select trunc(dbms_random.value(:lower_limit,:upper_limit),0) invoice_no
   from dual
  connect by level <= :number_of_rows
select invoice_no
  from (select invoice_no
          from invoices
--          where <your criteria here>
         order by dbms_random.value
where rownum <= :how_manyMessage was edited by:
Etbin