VBA/Excel/Access/Word/Data Type/Null

How Null Propagates

   <source lang="vb">

Sub nullDemo()

   Dim varFirstName   As Variant
   Dim varLastName   As Variant
   Dim varFullName   As Variant
   
   varFirstName = "Janine"
   varLastName = Null
   
   varFullName = varFirstName & varLastName
    
   Debug.Print varFullName

End Sub

</source>
   
  

Nulls are not equal

   <source lang="vb">

Sub CompareNulls()

   Dim varValue1 As Variant
   Dim varValue2 As Variant
   
   varValue1 = Null
   varValue2 = Null
   
   If varValue1 = varValue2 Then
       Debug.Print "Nulls are not equal"
   End If

End Sub

</source>
   
  

use IsNull function to check

   <source lang="vb">

Sub CompareNulls2()

   Dim varValue1 As Variant
   Dim varValue2 As Variant
   
   varValue1 = Null
   varValue2 = Null
   
   If IsNull(varValue1) And IsNull(varValue2) Then
       Debug.Print "Both variables are Null"
   End If
   

End Sub

</source>