how to customize ID Number.

[Coni]

How do I customize an ID as primary key to be anything other than numbers. For example what if I wanted to create an ID based on the last three letters of a last name and the extension number.

Thanks

[missinglinq]

For example what if I wanted to create an ID based on the last three letters of a last name and the extension number.

This is assuming that "extension" is a field in your table. In the code module of your form:

Private Sub Extension_AfterUpdate()
 If Not IsNull(Me.LastName) Then Me.IDNumber = Right(Me.LastName, 3) & Me.Extention
End Sub
 
Private Sub LastName_AfterUpdate()
 If Not IsNull(Me.Extension) Then Me.IDNumber = Right(Me.LastName, 3) & Me.Extension
End Sub 

This is kind of an unusual way to do this. Most schemes of this sort use the first three letters of a last name together with a number. Which would be

Private Sub Extension_AfterUpdate()
 If Not IsNull(Me.LastName) Then Me.IDNumber = Left(Me.LastName, 3) & Me.Extention
End Sub
 
Private Sub LastName_AfterUpdate()
 If Not IsNull(Me.Extension) Then Me.IDNumber = Left(Me.LastName, 3) & Me.Extension
End Sub 

Linq ;0)>

[NeoPa]

The question isn't very clear, and Linq's answer could well be all you need. However, it is also possible to design a table where these elements are stored separately in two fields, but the Primary Key is made up of both fields. A Composite Index.

In Design mode simpy select all the required fields and click on the Primary Index button.

Even in this case, the AfterUpdate technique could be used if the partial name is required to be garnered from the contents of another field.