Logic in single statment.

Question

1. if p_number is null then
     i have substitute 52211 value
2. if p_number is no exists in target table then
     i have substitute 52211 value
3. if p_number is exists in target table then
     i have take the target table value and i have do the some validation.
How to implement the above requirement in single statment.

Answer 1

If you want to do it by sql then this may help you!
Some sample data created for target table by with clause to make you understand. Id column is used for notifying your criteria to fetch number value from target table.
SQL> with target as
  2  (
  3     select 1 id, 12345 num_value from dual union all
  4     select 2, 54789 from dual union all
  5     select 3, null  from dual
  6  ),
  7  tab_52211 as
  8  (
  9     select 0 id, 52211 num_value from dual
10  )
11  select num_value res
12   from(
13     select id, nvl(num_value,52211) num_value from target where id = &p_number union all
14     select id, num_value from tab_52211
15     )
16  where rownum < 2 order by id desc
17  /
Enter value for p_number: 4
       RES
     52211
SQL> /
Enter value for p_number: 3
       RES
     52211
SQL> /
Enter value for p_number: 2
       RES
     54789