DataTableReader.IsDBNull Method

Gets a value that indicates whether the column contains non-existent or missing values.

Namespace: System.Data
Assembly: System.Data (in

Public Overrides Function IsDBNull ( _
	ordinal As Integer _
) As Boolean
Dim instance As DataTableReader
Dim ordinal As Integer
Dim returnValue As Boolean

returnValue = instance.IsDBNull(ordinal)
public boolean IsDBNull (
	int ordinal
public override function IsDBNull (
	ordinal : int
) : boolean
Not applicable.



The zero-based column ordinal

Return Value

true if the specified column value is equivalent to DBNull; otherwise, false.

Exception typeCondition


The index passed was outside the range of 0 to FieldCount - 1.


An attempt was made to retrieve data from a deleted row.


An attempt was made to read or access a column in a closed DataTableReader .

Call this method to see if there are null column values before calling the typed get methods (for example, GetByte, GetChar, and so on) to avoid raising an error.

The following example displays the contents of the column numbered 2 within the passed-in DataTableReader. If the value the column within a particular row is null, the code displays the text <NULL>. If the data within the column of the correct type, the example displays an error message for each row.

Private Sub PrintColumn(ByVal reader As DataTableReader)
   ' Loop through all the rows in the DataTableReader
   While reader.Read()
      If reader.IsDBNull(2) Then
         Catch ex As InvalidCastException
            Console.Write("Invalid data type.")
         End Try
      End If
   End While
End Sub

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

.NET Compact Framework

Supported in: 2.0

XNA Framework

Supported in: 1.0

Community Additions