vcl-403792-expressdatacontroller-vcl-data-controllers.md
A VCL Data Controller is an interlayer between a control that displays data and its underlying data source. DevExpress container controls (Tree List, Vertical Grid, Pivot Grid, or a View in the Data Grid) and certain data-aware editors rely on data controllers to access and shape data. Dedicated data controllers implement all available data access modes for supported products.
A control is not bound to a dataset and displays data cached in a data controller.
Refer to the following topic for information on how to create a master-detail relationship in the Data Grid: Unbound Mode: Master-Detail.
BoundA control relies on a data controller to load and shape data from a bound dataset. The TDataSource component connects the data controller to a dataset.Server
A control uses a server mode data controller to load data from a supported database on demand. The current server mode implementation supports Microsoft SQL Server, Microsoft Access, MySQL, Firebird, InterBase (except for query-based server mode data sources), Oracle, Advantage, PostgreSQL, and SQLite databases. A TdxServerModeDataController class descendant’s instance manages data.
Refer to the following topics for details on server mode:
ProviderA container control loads data from a custom data source (a TcxCustomDataSource class descendant). You can implement any data access and management mechanism in this mode.