Autoincrement dependent of other field - stored-procedures

Question

What is the best way to get an autoincrement "counter" thath depends of other field?.
Imagine this table
CUSTOMER - COUNTER
1 - 1
1 - 2
1 - 3
2 - 1
2 - 2
I need Counter increments 1 every record I add for every customer.
Regards.

Answer 1

Create additional table to hold counters for every customer:
CREATE TABLE customer_counter
(
customer_id INTEGER NOT NULL,
counter INTEGER NOT NULL,
PRIMARY KEY (customer_id)
)
Use following procedure to obtain next counter number for given customer:
CREATE PROCEDURE get_customer_counter (customer_id INTEGER)
RETURNS (counter INTEGER)
AS
BEGIN
SELECT SUM(counter) FROM customer_counter
WHERE customer_id = :customer_id
INTO :counter;
counter = COALESCE(:counter, 0);
EXECUTE STATEMENT
'INSERT INTO customer_counter (customer_id, counter) ' ||
'VALUES (' || :customer_id || ', 1)'
WITH AUTONOMOUS TRANSACTION;
END
See how we use sum and insert delta values instead of updating single record. Thus we prevent deadlocks.
On regular basis we need to clear counter table by merging delta records into one with a total value:
CREATE TRIGGER on_disconnect_database
ACTIVE
ON DISCONNECT
AS
DECLARE VARIABLE sm INTEGER;
DECLARE VARIABLE cnt INTEGER;
DECLARE VARIABLE customer_id INTEGER;
BEGIN
FOR
SELECT customer_id, SUM(counter), COUNT(counter)
FROM customer_counter
GROUP BY customer_id
INTO :customer_id, :sm, :cnt
DO BEGIN
IF (:cnt > 1) THEN
BEGIN
DELETE FROM customer_counter WHERE customer_id = :customer_id;
INSERT INTO customer_counter (customer_id, counter)
VALUES (:customer_id, :sm);
WHEN ANY DO
BEGIN
END
END
END
END

Answer 2

It's hard to really tell what you exactly want of what you have given, but I assume you want to loop through each X field and it's Y sub-field, use it for a counter, or whatever else.
<?php
$x = array("customer1","customer2","customer3");
$y = array("name","address","phone");
$counter;
foreach($x as $eachX):
$counter = 1;
foreach($y as $eachY):
//do stuff here
$counter++;
endforeach;
endforeach;
?>

Answer 3

I think this stored procedure will be ok!
create procedure New_Procedure
returns (
o_customer integer,
o_counter integer)
as
declare variable v_oldcostomer integer;
begin
for select customer
from customers
order by 1
into o_customer
do begin
if (v_oldcostomer is null or (v_oldcostomer is not null and v_oldcostomer <> o_customer) ) then
o_counter = 0;
o_counter = o_counter + 1;
v_oldcostomer = o_customer;
suspend;
end
end