PreExecute-Methode
Called after PrepareForExecute, and before PrimeOutput and ProcessInput.
Namespace: Microsoft.SqlServer.Dts.Pipeline
Assembly: Microsoft.SqlServer.PipelineHost (in Microsoft.SqlServer.PipelineHost.dll)
Syntax
'Declaration
Public Overridable Sub PreExecute
'Usage
Dim instance As PipelineComponent
instance.PreExecute()
public virtual void PreExecute()
public:
virtual void PreExecute()
abstract PreExecute : unit -> unit
override PreExecute : unit -> unit
public function PreExecute()
Hinweise
Component developers should factor as much functionality into PreExecute as possible because it is called one time per component instead of one time per buffer for ProcessInput. Components should locate the indexes of its input and output columns in the PipelineBuffer by calling the FindColumnByLineageID method of the BufferManager.
Beispiele
The following example shows how to locate the column indexes of the columns in the InputColumnCollection. They are stored in a local variable and then used in ProcessInput to access the columns in the PipelineBuffer.
int[] bufferColumnIndex;
public override void PreExecute()
{
IDTSInput100 input = ComponentMetaData.InputCollection[0];
bufferColumnIndex = new int[input.InputColumnCollection.Count];
for ( int x=0; x < input.InputColumnCollection.Count; x++)
{
bufferColumnIndex[x] = BufferManager.FindColumnByLineageID( input.Buffer, input.InputColumnCollection[x].LineageID);
}
}
public override void ProcessInput( int inputID, PipelineBuffer buffer )
{
while( buffer.NextRow() )
{
for( int x=0; x < bufferColumnIndex.Length(); x++ )
{
if( !buffer.IsNull(bufferColumnIndex[x]))
{
// TODO: Access the column data.
}
}
}
}
Private bufferColumnIndex As Integer()
Public Overrides Sub PreExecute()
Dim input As IDTSInput100 = ComponentMetaData.InputCollection(0)
bufferColumnIndex = New Integer(input.InputColumnCollection.Count - 1) {}
Dim x As Integer = 0
While x < input.InputColumnCollection.Count
bufferColumnIndex(x) = BufferManager.FindColumnByLineageID(input.Buffer, input.InputColumnCollection(x).LineageID)
x -= 1
End While
End Sub
Public Overrides Sub ProcessInput(ByVal inputID As Integer, ByVal buffer As PipelineBuffer)
While buffer.NextRow
Dim x As Integer = 0
While x < bufferColumnIndex.Length
If Not buffer.IsNull(bufferColumnIndex(x)) Then
End If
x -= 1
End While
End While
End Sub