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

# TDBComboBox

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

TDBComboBox is a data-aware version of TComboBox which allows selection of a value from a list of entries into a database field.

## Declaration

Source position: dbctrls.pp line 791

`type TDBComboBox = class(TCustomDBComboBox)`
`protected`
`procedure DataChange(); override;` |  | DataChange - updates the text if it has changed.
`procedure KeyPress(); override;` |  | Applies standard keystrokes to the control.
`procedure UpdateData(); override;` |  | Applies the changed value for the control to the field in its linked dataset.
`published`
`property Align: TAlign;` |  | Specifies the placement of the control on its Parent control.
`property Anchors: TAnchors;` |  | The set of anchor definitions for this control.
`property ArrowKeysTraverseList: Boolean;` |  | Indicates if keyboard Arrow (or cursor) keys can be used to move through the list.
`property AutoComplete: Boolean;` |  | Positions the list box using partial text matching.
`property AutoCompleteText: TComboBoxAutoCompleteText;` |  | Options for the behavior of the Auto-Complete feature.
`property AutoDropDown: Boolean;` |  | Indicates if the drop-down is automatically displayed when the control gets the input focus.
`property AutoSelect: Boolean;` |  | Selects the entire content of the edit box when the control receives the focus.
`property AutoSize: Boolean;` |  | Allows automatic adjustment of the size for the control, according to its content.
`property BiDiMode: TBiDiMode;` |  | Indicates whether text controls use in bi-directional reading.
`property BorderSpacing: TControlBorderSpacing;` |  | Determines the inner and outer border spacing for this control.
`property BorderStyle: TBorderStyle;` |  | Indicates the border style displayed around the control.
`property CharCase: TEditCharCase;` |  | Indicates the case conversion applied to the value entered in the edit box for the control.
`property Color: TColor;` |  | The background color for the control.
`property Constraints: TSizeConstraints;` |  | Contains the minimum and maximum Width and Height for the control.
`property DataField: string;` |  | The name of the Field which provides the values displayed in the control.
`property DataSource: TDataSource;` |  | Provides access to the dataset with content for the control.
`property DoubleBuffered: Boolean;` |  | When enabled, it reduces flicker when the control is painted.
`property DragCursor: TCursor;` |  | The cursor shape shown during a drag operation.
`property DragKind: TDragKind;` |  | Indicates the action performed for a drag operation: drag-and-drop or drag-and-dock.
`property DragMode: TDragMode;` |  | Determines how a drag operation is started for the control.
`property DropDownCount: Integer;` |  | The maximum number of Items visible in the drop-down list for the control.
`property Enabled: Boolean;` |  | Determines whether the control responds to mouse or keyboard input.
`property Font: TFont;` |  | The font to be used for text display in this control.
`property ItemHeight: Integer;` |  | The default height of an item in the drop-down for the control.
`property Items: TStrings;` |  | The list of items displayed in the combo-box control.
`property ItemWidth: Integer;` |  | The minimum width of the items in the drop-down list.
`property MaxLength: Integer;` |  | The maximum length for text entered in the edit box for the control.
`property ParentBiDiMode: Boolean;` |  | Indicates whether the BiDiMode settings in the Parent control are used.
`property ParentColor: Boolean;` |  | Use the Color from the Parent control, when enabled.
`property ParentDoubleBuffered: Boolean;` |  | Value for the DoubleBuffered property in a Parent control.
`property ParentFont: Boolean;` |  | Indicates if the Font from the Parent control is used in the control.
`property ParentShowHint: Boolean;` |  | If True, the value of ShowHint for the control will be the same as the one from the Parent. Default is True.
`property PopupMenu: TPopupMenu;` |  | A context-sensitive menu that pops up when the right mouse button is clicked over this control.
`property ReadOnly: Boolean;` |  | Indicates if the control is prevented from changing the field value in its linked dataset.
`property ShowHint: Boolean;` |  | Enables Hint display for the control.
`property Sorted: Boolean;` |  | Determines whether the list entries are sorted in alphanumeric order.
`property Style: TComboBoxStyle;` |  | Controls the appearance and behavior for the combo-box.
`property TabOrder: TTabOrder;` |  | Indicates the navigation order for the control when the user presses the Tab or Shift+Tab key.
`property TabStop: Boolean;` |  | Allows the user to navigate to / from the control by pressing the Tab or Shift+Tab keys.
`property Visible: Boolean;` |  | Indicates if the control is visible on its parent.
`property OnChange: TNotifyEvent;` |  | Event handler signalled for user changes to the text in the edit box.
`property OnChangeBounds: TNotifyEvent;` |  | Event handler signalled when the Bounds for the control have been changed.
`property OnClick: TNotifyEvent;` |  | Notification handler for mouse clicks.
`property OnCloseUp: TNotifyEvent;` |  | Handler invoked when the drop-down list closes.
`property OnContextPopup: TContextPopupEvent;` |  | Invoked when a context-sensitive pop-up menu is requested.
`property OnDblClick: TNotifyEvent;` |  | Event handler signalled when a mouse double click occurs in the control.
`property OnDragDrop: TDragDropEvent;` |  | Event handler signalled when an object is dropped onto the control.
`property OnDragOver: TDragOverEvent;` |  | Event handler signalled when a control is dragged over the control instance.
`property OnDrawItem: TDrawItemEvent;` |  | Handler for special painting of an item (in owner-draw mode).
`property OnDropDown: TNotifyEvent;` |  | Handler invoked when the list has dropped down.
`property OnEditingDone: TNotifyEvent;` |  | Event handler signalled when editing is completed for the control.
`property OnEndDrag: TEndDragEvent;` |  | Event handler signalled for the end of a drag-drop operation.
`property OnEnter: TNotifyEvent;` |  | Event handler signalled when the control receives focus.
`property OnExit: TNotifyEvent;` |  | Event handler signalled when the control loses focus.
`property OnKeyDown: TKeyEvent;` |  | Event handler signalled when a key is down while the control has focus.
`property OnKeyPress: TKeyPressEvent;` |  | Event handler signalled when a key is pressed while the control has focus.
`property OnKeyUp: TKeyEvent;` |  | Event handler signalled when when a key is released while the control has focus.
`property OnMouseDown: TMouseEvent;` |  | Event handler signalled when a mouse down event is handled for the control.
`property OnMouseEnter: TNotifyEvent;` |  | Event handler signalled when the mouse pointer has entered the control.
`property OnMouseLeave: TNotifyEvent;` |  | Event handler signalled when the mouse pointer has left the control.
`property OnMouseMove: TMouseMoveEvent;` |  | Event handler signalled when the mouse pointer is moved in the control.
`property OnMouseUp: TMouseEvent;` |  | Event handler signalled when a mouse up event is handled for the control.
`property OnMouseWheel: TMouseWheelEvent;` |  | Event handler for mouse wheel turned.
`property OnMouseWheelDown: TMouseWheelUpDownEvent;` |  | Event handler signalled for a downward movement of the mouse wheel.
`property OnMouseWheelUp: TMouseWheelUpDownEvent;` |  | Event handler signalled for an upward movement of the mouse wheel.
`property OnSelect: TNotifyEvent;` |  | Handler invoked when an item is selected.
`property OnStartDrag: TStartDragEvent;` |  | Event handler signalled for the start of a dragging operation.
`property OnUTF8KeyPress: TUTF8KeyPressEvent;` |  | Handler for a character entered by the user.
`end;`

## Inheritance

`TDBComboBox` |  | TDBComboBox is a data-aware version of TComboBox which allows selection of a value from a list of entries into a database field.
`TCustomDBComboBox` |  | TCustomDBComboBox is a data-aware combo-box for displaying information from a database.
`TCustomComboBox` |  | The base class for combo-box components.
`TWinControl` |  | Implements a windowed control which can contain other child controls.
`TControl` |  | The base class for visible controls.
`TLCLComponent` |  | The base class for LCL components which have an associated widget.
`TComponent`
?
`TObject`

## Description

TDBComboBox has properties similar to TComboBox and TCustomComboBox. It consists of an Edit Box which is the Data-aware part of the component, and a drop-down list box.

In a typical application a user would be presented with the drop-down list, would make a selection and then this would appear in the edit box and become the data value for that cell in the database.

As an example, a list of countries might be presented, and the selected value from the list would be used to populate the appropriate field ('Country') in that record of the database.

## See also

TCustomDBComboBox |  | TCustomDBComboBox is a data-aware combo-box for displaying information from a database.
How To Use Data-aware Controls |  | HowToUseDataAwareControls - Hints for accessing databases.