HELP with Update with Join

Ive been trying to get this to work for a while now and I cant find anything in the forum that works. I am using DB2 UDB v8.1 for windows. Here the problem:

I have 2 tables

Product Table
----
ID (Primary key)
Vendor_ID

Warehouse Table
-----
Product_ID (Foreign key to Product.ID)
Reorder_Level

I want to update all Warehouse.Reorder_Level on products that have a Vendor_ID of 1.

I have tried the following statements without any luck:

Update Warehouse set Reorder_Level=5 from Warehouse inner join Product on (Warehouse.Product_ID = Product.ID and Product.Vendor_ID=1)

Update (Select Warehouse.* from Product, Warehouse where Product.ID = Warehouse.Product_ID and Product.Vendor_ID=1) as temp set temp.Reorder_Level
=5

Update Warehouse, Product set Warehouse.Reorder_Level=5 where Product.ID = Warehouse.Product_ID and Product.Vendor_ID=1

Im out of ideas and very frustrated Please HELP!I don't know db2, but msql would be

UPDATE Warehouse
SET Reorder_level = 5
WHERE EXISTS
(SELECT *
FROM product
WHERE id = product_id AND vendor_id = 1)|||It works... Thank you!