Pure SQL question

[IT]

Hi all

This is not an omnis question, is pure sql challange.


I have an invoice table.

Customer	bill	date		amount
01		1	01/01/2011	12
01		3	02/02/2011	26
01		9	30/12/211	10
01		4	31/12/2011	15

02		2	02/01/2011	33
02		5	06/04/2011	15
02		6	05/08/2011	10
02		7	10/11/2011	5
02		8	30/12/2011	6


Now i have a selection of bills in a perior(1year) of bills in a  
table grouped by customer.
The select looks like:

select invoice.Customer, sum(invoice.amount) from invoice
where invoice.date between 01/01/2011 and 31/12/2011
group by invoice.Customer

The result looks like

Customer	amount
01		63
02		69


Now, I need the same selection of invoices in a period (1 year)  
grouped by customer but columns for every quarters

The select not sure how is, but the result must be something like:

Customer	Q1	Q2	Q3	Q4 	total
01		38	0	0	25	63
02		33	15	10	11	69


Any help how to make this quarter subtotals in sql ?

I'm new in sql and this is to much for me.

regards

xavier