PHP: Sum list of values

I have a list of information like this...

No. Customer Bank_Name Amount
-----------------------------
1.  AAA      Bank A    100 
2.  BBB      Bank B    200开发者_运维知识库 
3.  CCC      Bank A    500 
4.  DDD      Bank C    150 
-----------------------------
Total                  950 

How can I sum this information for each bank, using PHP, so the result looks like this...

No. Bank_Name Total
-------------------
1.  Bank A    600 
2.  Bank B    200 
3.  Bank C    150 
-------------------

If it's in a database... something like:

SELECT bank, SUM(amount) as `sum`
FROM customers
GROUP BY bank
ORDER BY bank