updating create view - error ORA-01779: - oracle

Question

I've used the CREATE VIEW command to create a view (obviously), and join multiple tables. The CREATE VIEW command works perfectly, but when I try to update the VIEW RentalInfoOct, I receive error "ORA-01779: cannot modify a column which maps to a non key-preserved table"
CREATE VIEW RentalInfoOct
(branch_no, branch_name, customer_no, customer_name, item_no, rental_date)
AS
SELECT i.branchNo, b.branchName, r.customerNo, c.customerName, i.itemNo, r.dateFrom
FROM item i
INNER JOIN rental r
ON i.itemNo = r.itemNo
INNER JOIN branch b
ON i.branchNo = b.branchNo
INNER JOIN customer c
ON r.customerNo = c.customerNo
WHERE r.dateFrom
BETWEEN to_date('10-01-2009','MM-DD-YYYY')
AND to_date('10-31-2009','MM-DD-YYYY')
My update command.
UPDATE RentalInfoOct
SET item_no = '3'
WHERE customer_name = 'April Alister'
AND branch_name = 'Kingsway'
AND rental_date = '10/28/2009'
I'm not sure if this will help in solving the problem, but here are my CREATE TABLE commands
CREATE TABLE Branch
(
branchNo SMALLINT NOT NULL,
branchName VARCHAR(20) NOT NULL,
branchAddress VARCHAR(40) NOT NULL,
PRIMARY KEY (BranchNo)
);
--Item Table Definition
CREATE TABLE Item
(
branchNo SMALLINT NOT NULL,
itemNo SMALLINT NOT NULL,
itemSize VARCHAR(8) NOT NULL,
price DECIMAL(6,2) NOT NULL,
PRIMARY KEY (ItemNo, BranchNo),
FOREIGN KEY (BranchNo) REFERENCES Branch ON DELETE CASCADE,
CONSTRAINT VALIDAMT
CHECK (price > 0)
);
-- Customer Table Definition
CREATE TABLE Customer
(
customerNo SMALLINT NOT NULL,
customerName VARCHAR(15) NOT NULL,
customerAddress VARCHAR(40) NOT NULL,
customerTel VARCHAR(10),
PRIMARY KEY (CustomerNo)
);
-- Rental Table Definition
CREATE TABLE Rental
(
branchNo SMALLINT NOT NULL,
customerNo SMALLINT NOT NULL,
dateFrom DATE NOT NULL,
dateTo DATE,
itemNo SMALLINT NOT NULL,
PRIMARY KEY (BranchNo, CustomerNo, dateFrom),
FOREIGN KEY (BranchNo) REFERENCES Branch(BranchNo) ON DELETE CASCADE,
FOREIGN KEY (CustomerNo) REFERENCES Customer(CustomerNo) ON DELETE CASCADE,
CONSTRAINT CORRECTDATES CHECK (dateTo > dateFrom OR dateTo IS NULL)
);

Answer 1

See: Oracle: multiple table updates => ORA-01779: cannot modify a column which maps to a non key-preserved table
You're attempting to update a view with joins, but the join conditions are not based on a uniqueness constraint, which creates the possibility of multiple rows that are created from a single row in one table.
It seems like you need a Unique Key - Foreign Key relationship between the columns your join condition is based on.
EDIT: I just saw your edit. Changing r.branchNo = b.branchNo to i.branchNo = b.branchNo should go a long way. Not sure how well r.customerNo = c.customerNo will work out.