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TClientDataSet: Temporary vs. permanent indices
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On TClientDataSets, that are not connected to a provider but loaded as local text files,
('thin client in brief-case mode'), you cannot use TQuerys.
You may use the .Filter property to select data and use an index to sort.
This sample code shows how to create a temporary index (not saved by SaveToFile())
and how to create a permanent index (saved by SaveToFile()):
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With ClientDataSet1 Do Begin Close; // Define the fields FieldDefs.Clear; FieldDefs.Add ('Project', ftInteger, 0, True); FieldDefs.Add ('Number', ftInteger, 0, False); // [..] // Define the PERMANENT index - it is saved with SaveToFile() IndexDefs.Clear; IndexDefs.Add ('IProject', 'Project', [ixPrimary, ixUnique]); // Create the dataset CreateDataSet; Open; // the following temporary index is not saved // with data when using SaveToFile() AddIndex('TempIndex', 'Number;Project', [ixPrimary, ixUnique]); End { with ClientDataSet1 } | ||
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