This sounds like you are trying an update via the import process. For this to work correctly, the model number field must be unique (i.e., every product record must have a different model number). But it doesn't sound like that's the case in your database, since you say you have the same model number in several categories as distinct product records. In this situation, you will have to update by product id rather than model number. One way to do this is to export the product ids of the products you want to update, change the prices, and then use the product ids for the update.
Bookmarks