IsNull 方法

Returns a value that indicates whether the value of the specified column is nullNothingnullptrunitnull 參考 (在 Visual Basic 中為 Nothing).

命名空間：  Microsoft.SqlServer.Dts.Pipeline
組件：  Microsoft.SqlServer.TxScript (在 Microsoft.SqlServer.TxScript.dll 中)

語法

'宣告
Protected Function IsNull ( _
    ColumnIndex As Integer _
) As Boolean
'用途
Dim ColumnIndex As Integer
Dim returnValue As Boolean

returnValue = Me.IsNull(ColumnIndex)

protected bool IsNull(
    int ColumnIndex
)

protected:
bool IsNull(
    int ColumnIndex
)

member IsNull : 
        ColumnIndex:int -> bool 

protected function IsNull(
    ColumnIndex : int
) : boolean

參數

• ColumnIndex
  型別：System. . :: . .Int32
  The index of the column.

傳回值

型別：System. . :: . .Boolean
true if the value of the specified column is nullNothingnullptrunitnull 參考 (在 Visual Basic 中為 Nothing); otherwise, false.

備註

The Script component developer does not use the ScriptBuffer class directly, but indirectly, through the derived classes in the BufferWrapper project item that represent the component's input and outputs.

The developer does not have to use the IsNull method, because the derived classes contain a <ColumnX>_IsNull property for each column.

範例

The following sample code from the autogenerated BufferWrapper project item demonstrates how the Script component uses the IsNull method.

    Public Property [city_IsNull] As Boolean
        Get
            Return IsNull(1)
        End Get
        Set
            SetNull(1)
        End Set
    End Property

請參閱

參考

ScriptBuffer 類別

Microsoft.SqlServer.Dts.Pipeline 命名空間