Checking for DBNull

19 Apr 2006 12:18 AM

Sreppohcdoow

Since Operator '==' cannot be applied to operands of type 'string' and
'System.DBNull'

What is the best way to accomplish:

if(myString == DBNull.Value)
myString=""

Thx,
MS

19 Apr 2006 1:25 AM

William (Bill) Vaughn

It really depends on your datatype.
Dim x As SqlTypes.SqlString = SqlTypes.SqlString.Null
If x.IsNull Then
x = ""
End If

works for SqlClient datatypes as they can be set to NULL. That said, the
untyped DataTable contains objects for all of the columns which can be NULL

So this works...

Dim y As Object = DBNull.Value
If y Is DBNull.Value Then
y = ""
End If

And so does this:

Dim z As String

If z Is DBNull.Value Then

z = ""

End If

If String.IsNullOrEmpty(z) Then

z = ""

End If

Make sense?

--

____________________________________
William (Bill) Vaughn
Author, Mentor, Consultant
Microsoft MVP
INETA Speaker
www.betav.com/blog/billva
www.betav.com
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Show quote

"Sreppohcdoow" <Sreppohcd***@asdf.com> wrote in message
news:%23OH5Vb0YGHA.4920@TK2MSFTNGP02.phx.gbl...
> Since Operator '==' cannot be applied to operands of type 'string' and
> 'System.DBNull'
>
> What is the best way to accomplish:
>
> if(myString == DBNull.Value)
> myString=""
>
> Thx,
> MS
>
>

19 Apr 2006 2:39 AM

Ryan Olshan

if (System.Convert.IsDbNull(SomeColumn)) { ... }

Thank you,
Ryan Olshan
     Website - http://www.StrongTypes.com
     Group - http://groups.yahoo.com/group/StrongTypes
     Blog - http://blogs.strongcoders.com/blogs/ryan/

Show quote

> Since Operator '==' cannot be applied to operands of type 'string' and
> 'System.DBNull'
>
> What is the best way to accomplish:
>
> if(myString == DBNull.Value)
> myString=""
> Thx,
> MS