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Borland_Delphi 2002-04-30
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不知道
日总是我哥 2002-04-30
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李维在他的书中说：我也很想知道Data的数据结构！
我不想~~~~
make11111 2002-04-30
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对!!!!!
loverlv 2002-04-30
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看了才知道
asdie 2002-04-30
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Data是OleVariant类型，它是一个代表midas数据包的变体，tclientdataset知道如何把这个数据包转化为可以使用的格式。他是受com子系统的数据集的限制，他可以作为从服务器返回数据的缓冲。
snowfog 2002-04-30
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cry
snowfog 2002-04-30
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why
snowfog 2002-04-30
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bluedreaming(蓝色海岸):
我已经得到了你说的特殊结构！我也知道Delta的作用！谢
我已经得到了你说的特殊结构！我也知道Delta的作用！谢
BlueDreaming 2002-04-30
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TClientDataSet的Data是用特殊格式封装的无状态(stateless)记录集而已;Belta则是Data中发生改变的记录集，当ApplyUpdates(0)时则是将Belta中的数据提交数据库！
snowfog 2002-04-30
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我是指如何把
PSafeArray = ^TSafeArray;
{$EXTERNALSYM tagSAFEARRAY}
tagSAFEARRAY = record
cDims: Word;
fFeatures: Word;
cbElements: Longint;
cLocks: Longint;
pvData: Pointer;
rgsabound: array[0..0] of TSafeArrayBound;
end;
这个结构，填充正确然后转换成oleVariant类型赋给Data!
PSafeArray = ^TSafeArray;
{$EXTERNALSYM tagSAFEARRAY}
tagSAFEARRAY = record
cDims: Word;
fFeatures: Word;
cbElements: Longint;
cLocks: Longint;
pvData: Pointer;
rgsabound: array[0..0] of TSafeArrayBound;
end;
这个结构，填充正确然后转换成oleVariant类型赋给Data!
CodeDuDu 2002-04-30
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这.........
GreenWaterBlueSky 2002-04-30
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OleVariant:可变类型
yuanjunjing 2002-04-30
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--看帮助
Represents the data of the client dataset in a transportable format.
property Data: OleVariant;
Description
Data represents the client dataset’s local, in-memory copy of its data, encoded as a data packet. This is the data in the binary format used internally by the client dataset.
This data packet can originate from a provider, a file on disk, or the Data property of another client data set.
Note: To obtain a copy of the client dataset’s data as an XML data packet instead of in a binary format, use the XMLData property.
----例子
This example shows how to use the OnDataRequest event to allow a client application to pass a filter expression to the provider and then receive only the records matching the filter.
The OnDataRequest event handler of the provider looks like the following:
function TForm1.Provider1DataRequest(Sender: TObject; Input: OleVariant): OleVariant;
begin
with (Sender as TDataSetProvider) do
begin
DataSet.Filter := Input;
DataSet.Filtered := True;
DataSet.First;
Result := Data;
end;
end;
On the client side, the DataRequest method can be used to fetch the data. The DataRequest method triggers an OnDataRequest event in the Provider component and returns the result of the event handler:
procedure TForm1.Button1Click(Sender: TObject);
begin
ClientDataSet1.Data := ClientDataSet1.DataRequest(FilterEdit.Text);
end;
Represents the data of the client dataset in a transportable format.
property Data: OleVariant;
Description
Data represents the client dataset’s local, in-memory copy of its data, encoded as a data packet. This is the data in the binary format used internally by the client dataset.
This data packet can originate from a provider, a file on disk, or the Data property of another client data set.
Note: To obtain a copy of the client dataset’s data as an XML data packet instead of in a binary format, use the XMLData property.
----例子
This example shows how to use the OnDataRequest event to allow a client application to pass a filter expression to the provider and then receive only the records matching the filter.
The OnDataRequest event handler of the provider looks like the following:
function TForm1.Provider1DataRequest(Sender: TObject; Input: OleVariant): OleVariant;
begin
with (Sender as TDataSetProvider) do
begin
DataSet.Filter := Input;
DataSet.Filtered := True;
DataSet.First;
Result := Data;
end;
end;
On the client side, the DataRequest method can be used to fetch the data. The DataRequest method triggers an OnDataRequest event in the Provider component and returns the result of the event handler:
procedure TForm1.Button1Click(Sender: TObject);
begin
ClientDataSet1.Data := ClientDataSet1.DataRequest(FilterEdit.Text);
end;
snowfog 2002-04-30
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i don't know, too!
linzhisong 2002-04-30
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不懂，愿闻其详！
dreamfan 2002-04-30
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不知道
