Less than or greater than Decode Function

Question

Can we use less than or greater than (relational operator) operator in decode function

Answer 1

Use Case instead.
Not sure if you need it in your resultset or your where clause.
Simple examples:
MHO%xe> with numbers as(
  2  select 1 a, 3 b from dual union all
  3  select 2 a, 3 b from dual union all
  4  select 3 a, 3 b from dual union all
  5  select 4 a, 3 b from dual union all
  6  select 5 a, 3 b from dual
  7  )
  8  select 'QRY1'
  9  ,      a
10  ,      b  
11  from   numbers
12  where (case when a >= b then 1 end) = 1
13  union all
14  select 'QRY2'
15  ,      case when a < b then b else 0 end
16  ,      case when b < a then a else 0 end
17  from numbers;
'QRY          A          B
QRY1          3          3
QRY1          4          3
QRY1          5          3
QRY2          3          0
QRY2          3          0
QRY2          0          0
QRY2          0          4
QRY2          0          5