Populate fields based on what's typed into first field

I have a paid-for database, originally in Access but migrated to SQL
Server 2008, and it contains the City, State, County, Latitude, and
Longitude for every zip code in the US.



In the form I have created, I want users to type in the Zip code, and
when they are done, the city and county text fields, and state
dropdown, would be populated with the correct data.



I've looked around to see if someone has done this, but I haven't
located any sample code for it. I assume it's going to be some
AJAX-type code, and I have a lot to learn about that kind of coding.



I am using Visual Studio 2008/.NET 3.5, and my language is VB.NET. (C# is not an option.)



thanks 


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