How to execute dynamic if statement...

Question

Hi All,
My PL/SQL Blocks looks like this
declare
i_string :='if 3>20 then 1 else 2 end if;' varchar2(100);
begin
end;
Between begin and end i want a piece of code which executes that if statement and sends 2 as output in dbms_output.put_line since 3 is not >20 .Basically i want to know how to execute dynamic if statement.Please help
Thanks,
Preethi

Answer 1

Hi,
i agree with Cyn. Dynamic SQL is often a bad idea. Try to avoid it.
Dynamic PL/SQL is even worse. If you really must do something dynamic, at least try to cast it as SQL rather than PL/SQL.
Does this do what you want?
CREATE OR REPLACE FUNCTION     eval_case
(     in_txt     IN     VARCHAR2
RETURN     NUMBER
DETERMINISTIC
IS
     return_val     NUMBER;
     sql_txt          VARCHAR2 (1000);
BEGIN
     sql_txt := 'SELECT  CASE '
          ||           in_txt
          || '         END'
          || '  FROM  dual';
     EXECUTE IMMEDIATE sql_txt INTO return_val;
     RETURN     return_val;
END     eval_case;
SHOW ERRORSYou might use the function above like this:
declare
     i_string  varchar2(100) :='WHEN 3>20 THEN 1 ELSE 2';
begin
     dbms_output.put_line (  TO_CHAR (eval_case (i_string))
                    || ' = results of eval_case ('''
                    || i_string
                    || ''')'
end;
/