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Frequently Asked Questions

Single Tier Applications

Question:

How do I set up a single tier application using Client Datasets?

Answer:

Currently, the only way to activate a client dataset at

design time is to associate it with a provider, to load

data from a file, or to assign data from another dataset.

Typically, for a single tier application you would create

the dataset at runtime using the CreateDataSet method.

Here is how you might code the FormCreate and FormDestroy

methods:

OnFormCreate: if FileExists('MYDATA.CDS') then ClientDataSet.LoadFromFile('MYDATA.CDS') else begin ClientDataSet.FieldDefs.Add('Field1', etc.); ClientDataSet.FieldDefs.Add('Field2', etc.); ClientDataSet.CreateDataset; end; OnFormDestroy: if ClientDataSet.Active then begin // Next line is optional, // if you don't want undo support you could // set LogChanges = False instead. ClientDataSet.MergeChangeLog; ClientDataSet.SaveToFile('MYDATA.CDS'); end;
Once you've run the app once and created the data file, you can easily load it at design time (from the right-click component menu) if you need to have the dataset active at design time for some reason.



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