auto fill field on a form when another field is updated

[woodpecker]

I am looking for the vba code to auto fill in the county when a zipcode is put into the zipcode field
I was thinking of a select case
the form is called frmpeople the fields are zipcode and county
I am not sure how the syntax is to be written exp:
Select Case Forms!frmPeople!ZipCode
Case is = 43611
County = Lucas


end Select
nothing happens

[Bob Fitz]

Do you have a table of zip codes and counties

[woodpecker]

yes I do have the table

[Bob Fitz]

One table or two. I would have expected two tables with a one to many relationship (One county can have many zipcodes).
Create a combo box on the form to show the zipcodes and counties with the county column hidden. Set the Control Source property of a text box on the form to reference the hidden column of the combo box.

[ArviLaanemets]

When you want only to display the county in form/report - create an unbound text box and use a formula to display a county (DLookup formula, or Bob's method)

When you want the county stored in same table (p.e. when you need to filter by county) - create a text box linked to county (code), disable editing for this text box, and set it's value in AfterUpdate event of control, you used to enter the ZIP code. In case you want to store county code, but to display it's name, use combo box instead of text box (but anyway disable editing).

[Bob Fitz]

When you want only to display the county in form/report - create an unbound text box and use a formula to display a county (DLookup formula, or Bob's method)

When you want the county stored in same table (p.e. when you need to filter by county) - create a text box linked to county (code), disable editing for this text box, and set it's value in AfterUpdate event of control, you used to enter the ZIP code. In case you want to store county code, but to display it's name, use combo box instead of text box (but anyway disable editing).

I believe that using DLookup() function will be slower