For more information about the IIf() function, in the Visual Basic Editor, click Microsoft Visual Basic Help on the Help menu, type IIf() in the Office Assistant or the Answer Wizard, and then click Search to view the topic.
For more information about the IsNull() function, in the Visual Basic Editor, click Microsoft Visual Basic Help on the Help menu, type IsNull() in the Office Assistant or the Answer Wizard, and then click Search to view the topic.
For more information about working with fields that contain no data, click Microsoft Access Help on the
Help menu, type About working with blank fields in queries in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.