RAD Studio VCL Reference
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Indicates the number or type of records in a single data packet.
property PacketRecords: Integer;
__property int PacketRecords;
Use PacketRecords to specify how many records should be contained in a single packet fetched from a provider, or to indicate that the packet returned should contain only metadata.
When a client dataset is instantiated, PacketRecords is automatically set to -1, meaning that a single packet should contain all records in the dataset.
If PacketRecords is greater than zero, then it specifies the number of records to return in a packet.
To retrieve the metadata for a dataset, set PacketRecords to 0. When PacketRecords is zero, the provider returns only information from its dataset that defines the database's structure, such as table, column, constraint, and domain definitions.
Delphi Examples:
{ This example shows how to use the BeforeGetRecords event handler (a TRemoteEventType value) to send the provider information it needs for incremental data fetching. Before fetching the next data packet, the client dataset packages up the key value of the last record so that the provider knows where to begin the next data packet. It also sends some application-specific information, which is stored in Memo1. This method is used to pass the sql statement and the value of the first field for the last record to the server so that the server can return the correct records. The complete project using this code example is in Demos/DelphiWin32/VCLWin32/MIDAS/Pooler. } procedure TForm1.ClientDataSet1BeforeGetRecords(Sender: TObject; var OwnerData: OleVariant); var LastValue: OleVariant; CDSClone: TClientDataSet; begin if ClientDataSet1.Active then begin CDSClone := TClientDataSet.Create(Form1); try CDSClone.CloneCursor(ClientDataSet1, True); { turn off FetchOnDemand so that the clone only fetches the last LOCAL record } CDSClone.FetchOnDemand := False; CDSClone.Last; LastValue := CDSClone.Fields[0].AsString; CDSClone.Close; finally CDSClone.Free; end; end else LastValue := NULL; OwnerData := VarArrayOf([Memo1.Lines.Text, LastValue]); end; procedure TForm1.Button2Click(Sender: TObject); begin ClientDataSet1.PacketRecords := StrToInt(Edit1.Text); ClientDataSet1.GetNextPacket; end;
Copyright(C) 2009 Embarcadero Technologies, Inc. All Rights Reserved.
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