Query for grouping by comparing sum of value for group

Is there a way using SQL to group data such that you're comparing the sum of a particular value against different values for each group? For example, consider the following schema:

Table: ITEM
Columns:
	ITEM_NUMBER (VARCHAR(15))
	QUANTITY_ON_HAND (DECIMAL(5,2))
Primary Key: ITEM_NUMBER

Table: ORDER_ITEM_REQUIREMENTS
Columns:
	ITEM_NUMBER (VARCHAR(15), Foreign Key to ITEM)
	DATE_ORDERED (TIMESTAMP)
	QUANTITY (DECIMAL(4,2))
	COST_PER (DECIMAL(10,2))
Primary Key: ITEM_NUMBER+DATE

Request: For each Item Number, order the Order Item Requirements in ascending order by Date, and get the maximum amount such that the sum of the Quantities is <= the Quantity On Hand for that Item Number (get all Order Item Requirements if the sum is less than the Quantity On Hand). Then output a result containing ItemNumber, NumShipments, QtySum, and CostSum (which is the sum of the product of CostPer and Quantity). If it matters, we're using IBM DB2 Version 7 Revision 3. ----- For example, given the following data:

{ITEM_NUMBER: "APPLE", QUANTITY_ON_HAND: 5}
{ITEM_NUMBER: "APPLE", DATE_ORDERED: Jan 1, 12:01, QUANTITY: 2, COST_PER: 1.23}
{ITEM_NUMBER: "APPLE", DATE_ORDERED: Jan 1, 12:02, QUANTITY: 2, COST_PER: 2.34}
{ITEM_NUMBER: "APPLE", DATE_ORDERED: Jan 2, 12:03, QUANTITY: 2, COST_PER: 5.55}

Or in terms of SQL:

CREATE TABLE MYLIB.ITEM (ITEM_NUMBER VARCHAR(15) NOT NULL NOT HIDDEN , QUANTITY_ON_HAND DECIMAL(5, 2) NOT HIDDEN , PRIMARY KEY (ITEM_NUMBER)  ) NOT VOLATILE UNIT ANY KEEP IN MEMORY NO ;

CREATE TABLE MYLIB.ORDER_ITEM_REQUIREMENTS (ITEM_NUMBER VARCHAR(15) NOT NULL NOT HIDDEN , DATE_ORDERED TIMESTAMP(6) DEFAULT CURRENT_TIMESTAMP NOT NULL NOT HIDDEN , QUANTITY DECIMAL(4, 2) NOT NULL NOT HIDDEN , COST_PER DECIMAL(10, 2) NOT NULL NOT HIDDEN , PRIMARY KEY (DATE_ORDERED, ITEM_NUMBER) , FOREIGN KEY (ITEM_NUMBER) REFERENCES MYLIB.ITEM (ITEM_NUMBER) ON DELETE NO ACTION ON UPDATE NO ACTION  ) NOT VOLATILE UNIT ANY KEEP IN MEMORY NO ;

INSERT INTO MYLIB.ITEM (ITEM_NUMBER, QUANTITY_ON_HAND) VALUES ('APPLE', 5);

INSERT INTO MYLIB.ORDER_ITEM_REQUIREMENTS (ITEM_NUMBER, QUANTITY, COST_PER) VALUES ('APPLE', 2, 1.23);
INSERT INTO MYLIB.ORDER_ITEM_REQUIREMENTS (ITEM_NUMBER, QUANTITY, COST_PER) VALUES ('APPLE', 2, 2.34);
INSERT INTO MYLIB.ORDER_ITEM_REQUIREMENTS (ITEM_NUMBER, QUANTITY, COST_PER) VALUES ('APPLE', 2, 5.55);

I would like the following result:

{ITEM_NUMBER: "APPLE", NUM_SHIPMENTS: 2, QTY_SUM: 4, COST_SUM: 7.14}