SQL Query to return N rows from dual

Question

I want to write a SQL query which accepts a bind variable (say :NUM) and its output consists of one column & :NUM number of rows, each row having its row number. i.e. if we

Answer 1

Another solution would require some PL/SQL to create a function to return a collection with the rows... Not as simple as the select level from dual connect by level <= :b1 approach, but it's useful in a few situations:

1) Create a number table object type ( number_tbl, in this example ) :

create or replace type number_tbl as table of number;

2) Create a function that will receive the number of rows to be generated, and then return a number_tbl object with the results:

create or replace function get_rows( i_num_rows number ) return number_tbl as
  t number_tbl := number_tbl();
begin
  if i_num_rows < 1 then
    return null;
  end if;

  t.extend( i_num_rows );

  for i in 1..i_num_rows loop
    t(i) := i;
  end loop;

  return t;
end get_rows;

3) select from your function using the table( ... ) function to turn your number_tbl object into something selectable:

select * from table( cast ( get_rows( :b1 ) as number_tbl ) );