multiple select multiple record

if i need to edit product information in my site,and i will select the available color for this product from dropdown multible select. but the value result in this form(red,blue,green)as i selected, and ineed to insert it in my db each color in new record as folowing:

product_name color

product1______ blue
product1______red
product1______ green
product2______blue
product3______green
product3______red