Microsoft Access has a rich set of functions when calculating values including the very popular IIF function. If you have used the IF function in an Excel spreadsheet, then you’ll feel at home here as it’s the same!
Take a quick look at the video below to know the basics
Microsoft Access IIF Function (IF/Then)
The above video was demonstrated with an earlier version of Microsoft Access and is still in use with the latest version (2010).
You can nest the IIF function (one function inside another) or any other function to really open up the flexibility of how users calculate with Microsoft Access queries, forms, reports and macros.