Call Create to instantiate a dataset component at runtime. TDataSet contains abstract methods, and is not intended to be used in applications. Instead, applications instantiate dataset descendants such as TClientDataSet, TADODataSet, TTable, TQuery, TStoredProc, or TSQLDataSet. 

AOwner is the component, typically a form or data module, that is responsible for freeing the dataset. It becomes the value of the Owner property. 

Create creates the auxiliary objects such as empty field and field definition lists and initializes default property values (such as setting AutoCalcFields to true). 

AutoCalcFields 

Destroy 

Owner