Evaluating a char variable which contains a Expression

Question

Hi,
I am creating a function ,which has got three parametrers and it should return a numeric value.
I will write down the function
create function fun1(expr varchar,res1 number,res2 number)return number
begin
if expr then
return res1;
else
return res2;
end if;
end;
This is my logic, expr parameter can have any expressions,eg: CTC+basic+hra>5000
my function should evaluate this and return the respective values.
Anybody please help me out for this issue.If you have some other logic to implement the same please do replay.
Regards
Rupesh

Answer 1

Here's a function (It can cause too many hard parses, I don't know any other solution for 9i)
declare
  function fun1(
    expr  varchar2,
    res1  number,
    res2  number)
    return number
  is
    res  number;
  begin
    execute immediate 'select :res1 from dual where ' || expr ||
                      ' union select :res2 from dual where not ' || expr
                 into res
                using res1, res2;
    return res;
  end;
begin
  DBMS_OUTPUT.put_line(fun1('1+1>1', 1, 2));
end;