[Overview][Constants][Types][Classes][Procedures and functions][Index] | Reference for unit 'DbCtrls' (#lcl)

# TDBLookup

[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

TDBLookup - used as source of data by TDBLookupListBox or TDBLookupComboBox, to find data from a lookup table

## Declaration

Source position: dbctrls.pp line 128

`type TDBLookup = class(TComponent)`
`protected`
`procedure Notification(); override;`
`procedure DoClearSelection;`
`public`
`constructor Create(); override;` |  | Create - constructor for TDBLookup: calls inherited Create, creates links with fields and data source, initialises ActiveChange and Editing properties
`destructor Destroy; override;` |  | Destroy - destructor for TDBLookup: frees links and calls inherited Destroy
`procedure Initialize();` |  | Initialize makes links between local Fields and the appropriate fields in the remote data source, then fetches the lookup data
`function ListFieldValue;`
`procedure UpdateData();`
`function GetKeyValue();`
`function GetListValue();`
`property LookupCache: Boolean; [rw]`
`property KeyField: String; [rw]` |  | The name of the KeyField used in the lookup search
`property ListField: String; [rw]` |  | ListField - the name of the list field used in the lookup search
`property ListFieldIndex: Integer; [rw]` |  | ListFieldIndex - the index value of the list field
`property ListSource: TDataSource; [rw]` |  | ListSource - the data source that contains the lookup list
`property NullValueKey: TShortcut; [rw]`
`property OnClearSelection: TNotifyEvent; [rw]`
`end;`

## Inheritance

`TDBLookup` |  | TDBLookup - used as source of data by TDBLookupListBox or TDBLookupComboBox, to find data from a lookup table
`TComponent,IUnknown,IInterfaceComponentReference`
`TPersistent`
`TObject`

## Description

TDBLookup component is typically owned by a Lookup control like TDBLookupListBox or TDBLookupComboBox.

The ListSource is the other dataset TDataSource from which to retrieve the lookup data

The KeyField is the lookup key in the ListSource which corresponds to the DataField value

The ListField is the name of the field in the ListSource to list into the Items property of the lookup control.

The latest version of this document can be found at lazarus-ccr.sourceforge.net .