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DataColumn.AllowDBNull Property

Gets or sets a value that indicates whether null values are allowed in this column for rows that belong to the table.

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

Public Property AllowDBNull As Boolean
Dim instance As DataColumn
Dim value As Boolean

value = instance.AllowDBNull

instance.AllowDBNull = value
/** @property */
public boolean get_AllowDBNull ()

/** @property */
public void set_AllowDBNull (boolean value)

public function get AllowDBNull () : boolean

public function set AllowDBNull (value : boolean)

Property Value

true if null values values are allowed; otherwise, false. The default is true.

The following example creates a new DataColumn and sets its AllowDBNull property to true.

Private Sub AddNullAllowedColumn()
    Dim column As DataColumn
    column = New DataColumn("classID", _
    column.AllowDBNull = True

    ' Add the column to a new DataTable.
    Dim table As DataTable
    table = New DataTable
End Sub

Windows 98, Windows 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 .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0