Why Null and IsNull exists? What is the use of it?

[makiwara]

So far it seems to me, that Nulls can be created only MANUALLY.

Like
dim var as variant
var = Null

And you can check this with isNull.


But you can never ever produce a Null value in any of the calculations, no matter what you do. Am I right in this? You can only use it if u create it MANUALLY.

So I don't understand why its useful. I could use instead of null any string for marking a variant, like "Sunshine".
If variant is Sunshine, I do something.

So what is the use of Null? I feel completely confused, sorry

 

[RoryA]

Null is mostly useful when working with databases, but it can actually be returned natively in Excel too. For example, if you were to test the Font.Color of a multiple cell range where one or more cells had a different font colour, it would return Null rather than a number.

 

[makiwara]

Null is mostly useful when working with databases, but it can actually be returned natively in Excel too. For example, if you were to test the Font.Color of a multiple cell range where one or more cells had a different font colour, it would return Null rather than a number.

Thank you for the idea.

Dim z As Variant
z = Range("A3:A4").Font.Color
Debug.Print z '0
Debug.Print IsNull(z) 'false

It would give back 0, but not Null. :/ I still don't understand this, seems overcomplicated.

 

[mikerickson]

With UserForm1.CheckBox1
    .TripleState = True
    .Value = Null
    If IsNull(.Value) Then MsgBox "Checkbox has third value"
End With

 

[RoryA]

Thank you for the idea.

Dim z As Variant
z = Range("A3:A4").Font.Color
Debug.Print z '0
Debug.Print IsNull(z) 'false

It would give back 0, but not Null. :/ I still don't understand this, seems overcomplicated.

Make A3 a different font colour to A4, then run the code again.