REPLACE INTO need to have a added field

I am trying to use REPLACE INTO to update a table. It is working fine but I would like to have 2 fields:
datetime - Added to table
datetime - Updated

The Updated datetime is fine but I cant work out how to not 'update' the Added to Table field. I just want a field that records the datetime that the record was first added to my table.

Any ideas?

Thanks

 

update tblName set Updated = nnn where ...
Added to Table field will be the same

 

Cheers for the reply. I eventually came up with the following solution:

INSERT INTO myTable ( data.......... CreateTime Now())ON DUPLICATE KEY UPDATE (data............UpdateTime Now())

So INSERT into myTable if the Primary Key Duplicate error UPDATE the myTable.
So I dont need to see if a record exists before choosing to INSERT or UPDATE.