Creating a complex ID using a trigger - oracle

Question

In many of our applications we use an identity column to generate a unique number, such as a customer_id.
Our internal auditors feel this is a possible breach of security and going forward we want to use something a bit more complex.
I found a function below base34 that I want to pass a concatenation of SYS_Guid, part of a TIMESTAMP and a sequence number to create a more complex ID.
Below is my test CASE. Is there a way I can use the base34 function in a before INSERT trigger with the above concatenation without changing the base34 function to achieve this task.
For example, let's say I have the following table.
CREATE TABLE CUSTOMERS (
customer_id VARCHAR2 (20),
first_name VARCHAR2 (20),
last_name VARCHAR2 (20));
And I want the trigger to populate customer_id
Thanks in advance for your time and expertise.
create table t ( pk number);
create sequence seq start with 1000000 minvalue 1000000 maxvalue 9999999 cycle;
begin
for i in 1 .. 10 loop
insert into t values ( to_number(trunc(dbms_random.value(1000,9999))|| to_char(systimestamp,'FFSS')||
seq.nextval));
end loop;
end;
/
create or replace function base34(p_num number) return varchar2 is
l_dig varchar2(34) := 'AB0CD1EF2GH3JK4LM5NP6QR7ST8UV9WXYZ';
l_num number := p_num;
l_str varchar2(38);
begin
loop
l_str := substr(l_dig,mod(l_num,34)+1,1) || l_str ;
l_num := trunc(l_num/34);
exit when l_num = 0;
end loop;
return l_str;
end;
/
create or replace function dec34(p_str varchar2) return number is
l_dig varchar2(34) := 'AB0CD1EF2GH3JK4LM5NP6QR7ST8UV9WXYZ';
l_num number := 0;
begin
for i in 1 .. length(p_str) loop
l_num := l_num * 34 + instr(l_dig,upper(substr(p_str,i,1)))-1;
end loop;
return l_num;
end;
/
select base34(pk) from t where rownum <= 10;
select to_char(pk) from t where rownum = 1
union all
select base34(pk) from t where rownum = 1
union all
select to_char(dec34(base34(pk))) from t where rownum = 1;

Answer 1

CREATE TABLE CUSTOMERS (
customer_id VARCHAR2 (20),
first_name VARCHAR2 (20),
last_name VARCHAR2 (20));
create sequence seq start with 1000000 minvalue 1000000 maxvalue 9999999 cycle;
create or replace function base34(p_num number) return varchar2 is
l_dig varchar2(34) := 'AB0CD1EF2GH3JK4LM5NP6QR7ST8UV9WXYZ';
l_num number := p_num;
l_str varchar2(38);
begin
loop
l_str := substr(l_dig,mod(l_num,34)+1,1) || l_str ;
l_num := trunc(l_num/34);
exit when l_num = 0;
end loop;
return l_str;
end;
CREATE OR REPLACE TRIGGER customer_trg
BEFORE INSERT
ON customers
FOR EACH ROW
BEGIN
:NEW.customer_id := base34(to_number(trunc(dbms_random.value(1000,9999))|| to_char(systimestamp,'FFSS')||
seq.nextval));
END;
begin
for i in 1 .. 100 loop
INSERT into customers (first_name, last_name) VALUES ('John', 'Doe');
end loop;
end;
/