Making a procedure to work against 8i, 9i and 10g databases

Question

Hello all,
I made a procedure that gathers info from user. At some point I execute this part of code:
CURSOR tabPrivs IS
SELECT owner, table_name, privilege, grantable, hierarchy
FROM dba_tab_privs
WHERE grantee = uName;
At first my procedure was only for 9i and 10g databases. I tried it once on 8i and get the logical error that the hierarchy column doesn't exist in the table dba_tab_privs.
I want my procedure to work against all versions of databases so I tried to do an additional select if the database version was upper than 8, but it seems that it won't compute, as if before executing my procedure, the engine look to all the select I am trying to do and check if they are correct.
I want to know if there's a work-around because I want to provide the most generic procedure possible.
Thank you,

Answer 1

You need to declare your cursor according to your DB version. Something like this might keep you going:
DECLARE
   VERSION         VARCHAR2 (30);
   COMPATIBILITY   VARCHAR2 (30);
   uname           VARCHAR2 (30);
   TYPE cur IS REF CURSOR;
   p_sys           cur;
BEGIN
   DBMS_UTILITY.db_version (VERSION, COMPATIBILITY);
   IF VERSION LIKE '10%' OR VERSION LIKE '9%'
   THEN
      OPEN p_sys FOR 'SELECT owner, table_name, PRIVILEGE, grantable, HIERARCHY
           FROM dba_tab_privs
          WHERE grantee = :uname' USING uname;
   ELSIF VERSION LIKE '8%'
   THEN
      OPEN p_sys FOR 'SELECT owner, table_name, PRIVILEGE, grantable
           FROM dba_tab_privs
          WHERE grantee = :uname' USING uname;
   END IF;
   do_your_fetch_and_work_here;
   CLOSE p_sys;
END;