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Datasnap.DBClient.TCustomClientDataSet

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Data.DB.TDataSetSystem.Classes.TComponentSystem.Classes.TPersistentSystem.TObjectTCustomClientDataSet

Delphi

TCustomClientDataSet = class(TDataSet, IDataSetCommandSupport)

C++

class PASCALIMPLEMENTATION TCustomClientDataSet : public Data::Db::TDataSet

Properties

Type Visibility Source Unit Parent
class public
Datasnap.DBClient.pas
Datasnap.DBClient.hpp
Datasnap.DBClient Datasnap.DBClient

Description

TCustomClientDataSet is the base class for datasets that cache their data in memory.

TCustomClientDataSet represents an in-memory dataset that stores its data in transportable data packets. On Windows, it relies on Midas.dll or Midaslib.dcu, and On Linux, it relies on midas.so to provide the underlying support for managing database operations such as navigating records, posting records to a change log, filtering records, and so on.

There are two basic ways a client dataset can obtain its data and apply its updates:

  • It can read from and write to a dedicated file on disk, acting as a file-based dataset.
  • It can obtain records from another dataset and post updates to that dataset or its database server. When working with another dataset, the client dataset communicates with that source dataset using a dataset provider. Depending on the TCustomClientDataSet descendant, the provider and the source dataset can be external to the client dataset, or they can be internal, owned objects.

Client datasets are used primarily for caching updates or to represent the dataset in the client portion of a multi-tiered database application.

Do not create instances of TCustomClientDataSet. TCustomClientDataSet is intended only as a base class for datasets that store data in memory as data packets. To add this functionality to a database application, use a TCustomClientDataSet descendant such as TClientDataSet, TBDEClientDataSet, or TSQLClientDataSet.

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