Using Access 2007:

I have a table called "Staff" with three fields "firstName", "lastName" and "fullName";
and a form with three bound text boxes bound to these values:

How can i update automatically change the value of fullName to inlcude firstName and last name?

For example:
firstName = Trek
lastName = Mietta

then fullName should automatically change to: "Trek Mietta" (With a space inbetween them)

Thanks in Advance

You should not store the full name in a table field. To do so is a breach of normalization.
Where you need to work with the whole name you should create it as required in a query or textbox.
The Control Source of the textbox on the form:
[firstname] & " " & [lastname]

As GalaxiomAtHome said, you should not be trying to store the concatenated field but instead you use a query to do so and display it to whatever you need (remember, you can use a QUERY almost wherever you can use a table).

Okay thanks people i will try that and see if it works!

OKay your probably going to shout at me here for suggesting concatenating two fields again but this would make life so much easier:

Again I have the table called "Staff" with three fields "firstName", "lastName" and "username";
and a form with three bound text boxes bound to these values:

How can i update automatically change the value of username to inlcude firstName and lastName?

For example:
firstName = Trek
lastName = Mietta

eg: username = "firstName.lastName"
(With a period "." in between them and all lowercase)

Thanks in Advance

still not!

if you need it assembling like that just say

forename & "." & lastname

Okay thank you for your help

Again, I will state - you do NOT need to add it to the table. If you build a query which displays all fields including that concatenated one, you can use that query in place of a table where you would be using a table.