Dealing with DBNull results in a Datareader

[oddball]

Always have this problem whenever a DB query returns Null values for certain columns to my Datareader. I don't know how to check if any of the values returned are Null before setting the control Text property or SelectedIndex to it.

With the code below i get the following error message:

"Cast from type 'DBNull' to type 'String' is not valid"

===========================================================

Dim allocatedDA As Integer
Dim dr_id As SqlDataReader = users.GetSingleUserID(userId)

dr_id.Read()

allocatedDA.Text = CInt(dr_id("DA&quot)

dr_id.Close()

===========================================================

I have tried this:

===========================================================

If Not IsDBNull(dr_id("UserID&quot) Then

blahblah

End If

===========================================================

And this:

===========================================================

If Not (dr_id("UserID&quot) = Nothing Then

blahblah

End If

===========================================================

Aswell as this:

===========================================================

If Not (dr_id("UserID&quot) Is Nothing Then

blahblah

End If

===========================================================

But none of them seem to work! Help please.

cheers,

si

 

[rveer]

Try this:

If Not dr_id("UserID") is DBNull Then

    blahblah

End If

The cast warning '"Cast from type 'DBNull' to type 'String' is not valid"' gives a hint to the solution. You cannot convert a DBNull into a string. Therefore you should check the type of the object..

 

[oddball]

cheers

 

[oddball]

Tried it and i now get this error:

"'DBNull' is a type and cannot be used as an expression."

what else can i try,

cheers,

si

 

[link9]

If Not isDBNull(dr_id("UserID&quot) Then