Insert or update if record is in table

Question

I have a tables Cars and CarDescriptions

cars: IDCar(int, PK, autoincrement) carsDesciptions(IDDescription, Header(nvarchar),Content(nvarchar),idCar(int,FK)

In application I am adding cars and editing existing ones.

My problems:

1.How to save changed Car with descriptions in database ??

I have ID of Car, and I have ID's of Descriptions

Class CarDescirption doesn't have any pool like IsChanged, so

I don't wanna do something like :

1. delete from carsdescriptions where idcar=@idcar
2. insert into cardescriptions (, @Header,@Content,@IDCar)

the record must be updated if is in table, and inserted if doesn't exist in table

Answer 1

It has the best perfomacne:

UPDATE Table1 SET (...) WHERE Column1='SomeValue'
IF @@ROWCOUNT=0
    INSERT INTO Table1 VALUES (...)