how to create a trigger for certain rows?

[William Lou]

I'm newbie to triggers. I don't know if it's possible to create a trigger which won't be fired by each row but only by certain rows. For example, I have a table A with two columns `product_ID`, `product_type`, and then I wan to create a trigger on table A which will be fired only when a certain product ( where `product_type` = 'TV' etc..) is inserted into table A. How could I put the condition into the trigger that it will only be fired when a record with type 'TV' is inserted into the table? Thanks for your help!