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TDataSet is the base class for all dataset components that represent data in rows and columns. Unit db Description TDataSet encapsulates a database-engine independent set of properties, events, and methods for working with data. Many of the properties, events, and methods in TDataSet are abstract. Abstract declarations are declarations without implementations. At the TDataSet level they cannot be used or accessed. Developers must use or derive descendants of TDataSet that declare and implement these abstract methods. Many of the other TDataSet methods are declared and implemented in TDataSet as virtual methods, but the implementations are merely stubs that are reimplemented in descendants such as TClientDataSet, TBDEDataSet, TDBDataSet, TQuery, TStoredProc, and TTable. Single-tiered applications that use flat-file data and multi-tiered database applications that use distributed datasets access their data using TClientDataSet, a direct descendant of TDataSet. Developers who develop their own distributed dataset objects should derive them from TClientDataSet as well. Applications that base their data access on ActiveX Data Objects (ADO) use TADODataSet, another direct descendant of TDataSet, or the more specific descendants TADOTable and TADOQuery. Traditional single-tiered and two-tiered database applications that access data through the Borland Database Engine (BDE) use TQuery, TStoredProc, or TTable objects. Developers who create custom dataset components that use the BDE directly in a client application derive them from TBDEDataSet, TDBDataSet, TQuery, TStoredProc, or TTable. |
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