Concatenating 2 Table Fields To Form Another

Hi all,

Ive got a table called tblClientCar, this is its structure:

ClientCarID
ClientID
CarID

I want to use an append query to concatenate ClientID and CarID together and putting the concatenated value into ClientCarID. How would i do this?

Ive tried using a form a two combos so when i select the clientID from the 1st combo and then the CarID from the 2nd combo, then run the append query to write the concatenated value into ClientCarID of the table. But it says writing 0 rows to table and the ClientCarID isnt concatenated when i check the table. This is the query sql syntax i was using:

INSERT INTO tblClientCar ( ClientCarID, ClientID, CarID )
SELECT tblClientCar.ClientCarID, tblClientCar.ClientID, tblClientCar.CarID
FROM tblClientCar
WHERE (((tblClientCar.ClientCarID)=[Forms]![frmClientCar].[Combo6] & "" & [Forms]![frmClientCar].[Combo8]));

I also tried another way. The 2 combos add the selected values into ClientID and CarID in the table tblCar. So i made the append query slightly different to concatenate ClientID and CarID to form ClientCarID. This is my query sql syntax:

INSERT INTO tblClientCar ( ClientCarID, ClientID, CarID )
SELECT tblClientCar.ClientCarID, tblClientCar.ClientID, tblClientCar.CarID
FROM tblClientCar
WHERE (((tblClientCar.ClientCarID)=[ClientID] & "" & [CarID]));

I get the same result as the 1st query. What am i doing wrong?
Is there another way of doing what im trying to do? Whats the correct sql syntax for doing this?

Thanks
Jim