How I update single MySQL cell with 3 or more table Fields?

How I update MySQL with 3 table Fields? I have products in the store but I have different sizes and colours and I want to create a shortcode for the specific products which includes size and colour..

So
Feild1 = [product short code]
Field 2 = [size short code]
Field 3 = [colour short code]

and the end product is:

[Unique product name]-[size short code]-[colour short code]

Example:

PD002-XL-GRN
(Product2-ExtraLarge-Green)

I need this to be generated as I'm adding or updating the product information. I was thing of adding additional hidden fields and adding additional mini queries to call up the short codes and put them together in the hidden field.

create recordsets to look up the product size and color values, use the recordsets to populate the lists

I thought that would be the case... thanks for confirming.