PLSQL function if not available do else - oracle

Question

In my oracle 11 environment I have declared following function (successfully, no errors).
create or replace function s2_encrypt(paramToEncrypt in VARCHAR2, encrypt8BYTEKey in RAW)
return RAW is encryptedReturnValue RAW (2000);
encryptionMode number := DBMS_CRYPTO.ENCRYPT_AES128 + DBMS_CRYPTO.CHAIN_CBC + DBMS_CRYPTO.PAD_PKCS5;
begin
encryptedReturnValue := dbms_crypto.encrypt(UTL_I18N.STRING_TO_RAW(paramToEncrypt, 'AL32UTF8'), encryptionMode, encrypt8BYTEKey);
return encryptedReturnValue;
end;
/
found here: http://anujktyagi.blogspot.ch/2012/12/oracle-using-dbmscrypto-package-for.html
I am deploying this on several servers, some of which only run Oracle version 8 / 9 -> in which case I want to just copy the value (instead of decrypting it).
How would I extend the above function so that it can be deployed both in Oracle 10+ and lower (in later case just copy paste the value and not encrypt)?
Something like
create or replace function s2_encrypt(paramToEncrypt in VARCHAR2, encrypt8BYTEKey in RAW)
return RAW is encryptedReturnValue RAW (2000);
encryptionMode number := DBMS_CRYPTO.ENCRYPT_AES128 + DBMS_CRYPTO.CHAIN_CBC + DBMS_CRYPTO.PAD_PKCS5;
begin
...
if !dbms_crypto.encrypt exit ???
...
encryptedReturnValue := dbms_crypto.encrypt(UTL_I18N.STRING_TO_RAW(paramToEncrypt, 'AL32UTF8'), encryptionMode, encrypt8BYTEKey);
return encryptedReturnValue;
end;
/

Answer 1

You can use conditional compilation
using package DBMS_DB_VERSION or some of your constants
$IF DBMS_DB_VERSION.ver_le_9_1 $THEN
return paramToEncrypt ;
$ELSE
encryptedReturnValue := dbms_crypto.encrypt(UTL_I18N.STRING_TO_RAW(paramToEncrypt, 'AL32UTF8'), encryptionMode, encrypt8BYTEKey);
return encryptedReturnValue;
$END

Answer 2

The most sensible approach would be to use two separate versions of the function - one for version 8/9 and one for 10.
That being said, the following approach should work (untested, I don't have access to any instances running Oracle 10 or lower):
check the database version (either by checking the existence of DBMS_DB_VERSION or by parsing the output of PRODUCT_COMPONENT_VERSION or V$VERSION which - to the best of my knowledge - already existed in version 8).
use dynamic SQL to either call dbms_crypto or return the string unchanged (since your package won't compile on 8/9 if you reference dbms_crypto directly)
Example (untested):
create or replace function s2_encrypt(paramToEncrypt in VARCHAR2,
encrypt8BYTEKey in RAW) return RAW is
encryptedReturnValue RAW(2000);
objectCount pls_integer;
begin
select count(*)
into objectCount
from all_objects
where object_name = 'DBMS_CRYPTO';
-- Oracle 8/9: return string unchanged
if objectCount = 0 then
encryptedReturnValue := paramToEncrypt;
else
execute immediate '
declare
encryptionMode number := DBMS_CRYPTO.ENCRYPT_AES128 + DBMS_CRYPTO.CHAIN_CBC + DBMS_CRYPTO.PAD_PKCS5;
begin
:encryptedReturnValue := dbms_crypto.encrypt(UTL_I18N.STRING_TO_RAW(:paramToEncrypt, ''AL32UTF8''), encryptionMode, :encrypt8BYTEKey);
end;'
using out encryptedReturnValue, in paramToEncrypt, in encrypt8BYTEKey;
end if;
return encryptedReturnValue;
end;
Usage (11g - 8i apparently did not have UTL_I18N, see comments)
select s2_encrypt(
'hello world',
UTL_I18N.STRING_TO_RAW ('8232E3F8BDE7703C', 'AL32UTF8'))
from dual;

Answer 3

You can use Conditional Compilation available from Oracle 10g Release 1.
See https://oracle-base.com/articles/10g/conditional-compilation-10gr2
In older versions you can just use a normal IF-ELSE statement
DECLARE
v1 VARCHAR2 (10);
v2 VARCHAR2 (10);
BEGIN
DBMS_UTILITY.db_version (v1, v2);
IF SUBSTR (v1, 1, INSTR (v1, '.', 1)-1) < 10 THEN
returnvalue paramToEncrypt;
ELSE
returnValue := dbms_crypto.encrypt(UTL_I18N.STRING_TO_RAW(paramToEncrypt, 'AL32UTF8'), encryptionMode, encrypt8BYTEKey);
END;
return returnValue;
END;