Dynamically how to calculate expression through PL/SQL ..?

Question

My senario like...
I want to calculate the expression using array values from input parameter and then I want to send that calculated values as a output parameter.
How to do through PL/SQL..?
I am passing two parameter.
1. expression variable value as array,
2. expression as string
I want to execute that expression using Execute immediate or any other way through PL/SQL.
For Example,
exec myPL_SQLproc(p1,p2)
p1,p2 = (1,2,3), 'a*(a+10)-b+c'
p1,p2 = (1,2,3,4,5), '((a+b+c+d+e)+(a-b-c-d-e))*log(a)' here base10 for log(a).
here p1 is array (pl/sql table type)
p2 is string (expression: varchar2 type)

Answer 1

Although I think this is likely to be a bad design decision, you can use something like:
DECLARE
   TYPE values_tp IS VARRAY(10) OF NUMBER;
   l_values_tp values_tp := values_tp(1,2,3);
   l_expr VARCHAR2(25) := 'a*(a+10)-b+c';
   l_exec VARCHAR2(25);
   l_result NUMBER;
BEGIN
   FOR i IN 1 .. l_values_tp.COUNT LOOP
      l_expr := REPLACE(l_expr, CHR(96+i), l_values_tp(i));
   END LOOP;
   DBMS_OUTPUT.Put_Line(l_expr);
   EXECUTE IMMEDIATE 'SELECT '||l_expr||' FROM dual' INTO l_result;
   DBMS_OUTPUT.Put_Line('Result is '||l_result);
END;Minimally, you should check the formula string for things like semi-colons (;) and two consecutive hyphen (--) which could indicate a sql injection attempt. You would also probably need much more error handling.
TTFN
John