Procedure to generating an ID

Question

Oracle Database 10g Enterprise Edition Release 10.1.0.5.0
create table INV
(inv_id VARCHAR2(26) not null);
INSERT INTO inv
     (inv_id)
VALUES
     ('ABC');
INSERT INTO inv
     (inv_id)
VALUES
     ('ABC.');   
INSERT INTO inv
     (inv_id)
VALUES
     ('ABC..');
select * from invWhat I want to do is create a procedure with an INPUT of a inv_id value and loop thru the records to generate a unique ID
for example the above if I input ABC I want to loop and check to see if there is already a record there
so it should loop and if found add a '.' to the end of 'ABC' and keep looping until it had 3 '...' at the end, hence it being unique.
What I want to output is an Inv_id of 'ABC...'
apologies if it is not clear. my logic head is out the window today.
thanks.

Answer 1

Or the equivalent using NLV2 function...
SQL> ed
Wrote file afiedt.buf
  1  select nvl2(max(inv_id),max(inv_ID)||'.','ABC') as inv_id
  2  from   inv
  3* where  inv_id like 'ABC%'
SQL> /
INV_ID
ABC...