ComboBox

Description

The component is used to show/select the record.

Class: TdbComboBox

Properties

Property	Type	Description
sqlValue	String	Returns the id of the selected record in the component, for use in SQL queries. In case of empty value, it returns NULL string example: SQLExecute ('INSERT INTO tablename (fieldname) VALUES ('+Form1.ComboBox1.sqlValue+')');
dbItemID	Integer	The identifier of the selected record in the component. The identifier corresponds to the id field in the database. If no entry is selected, returns -1
dbSortField	String	The database field by which the records in the component will be sorted.
dbSortAsc	Boolean	If True, the records will be sorted in ascending order, otherwise in descending order.
dbFilter	String	Allows you to set an additional filter that will be used to fill the component with data from the database. For example: tablename.fieldname = 1
dbForeignKey	String	Specifies which external key of the database table this component belongs to.
dbField	String	Determines which field of the database table this component belongs to.
dbIncremSearch	String	Allows you to specify the name of the button on the current form with the "Search" or "SQL query" action, which will be automatically pressed when user changes the value of the component. The property is necessary to implement instant search.
dbSQL	String	Contains the SQL query that was used when the SQLExecute method was called.
CanFocus	Boolean	It checks if the component can get input focus, which is usually necessary before using the SetFocus method. If a component has Visible = False or Enabled = False property, or if the component is located on a parent component with those properties, using the SetFocus method will cause an error. example: if Form1.ComboBox1.CanFocus then Form1.ComboBox1.SetFocus;
Color	TColor	Specifies the background color of the control. More info.
Cursor	TCursor	Specifies the image used to represent the mouse pointer when it passes into the region covered by the control. More info.
DroppedDown	Boolean	Indicates whether the drop-down list is currently displayed.
Enabled	Boolean	Controls whether the component responds to mouse, keyboard, and timer events.
Focused	Boolean	Determines whether the control has input focus.
Font	TFont	Allows you to set font name, size, color and style. More info.
GetCount	Integer	Allows you to get the number of records in a component.
HideTextIfNotExists	Boolean	Makes sense if the Searchable property = True. Set HideTextIfNotExists = False, so that the entered text will not disappear if it is not found among records.
Hint	String	Hint contains the text string that appears when the user moves the mouse over the component., see also ShowHint
ItemIndex	Integer	Specifies the index of the selected item. The first item in the list has index 0, the second item has index 1, and so on. If no item is selected, the value of ItemIndex is -1.
Items	TStringList	Provides access to the list of items (strings) in the list portion of the combo box. More info.
Items[i]	String	Line-by-line access to the list of records. Example: ShowMessage(Form1.ComboBox1.Items[1]); // will show a message with the second line (numbering from zero
ItemsChecked[i]	Boolean	Makes sense if the MultiSelect = True property allows you to read or check the checkbox next to the record.
MultiSelect	Boolean	Enables multiple selection of records in the component. Applies when using the button with the "Search" action or a script.
Name	String	The name of the component.
ShowHint	Boolean	Specifies whether to show the Help Hint when the mouse pointer moves over the component, see also Hint
SearchableType	TSearchType'	It makes sense if the Searchable property = True. Search Type. Values: stExact - search for full match, stContain - search for substring in string.
SelectedCount	Integer	Makes sense if the MultiSelect property = True. Returns the number of selected records in the component.
SelLength	Integer	Specifies the length, in characters, of the selected text in the edit portion of the combo box.
SelStart	Integer	Specifies the position of the first selected character in the edit portion of the combo box.
Sorted	Boolean	Determines whether the records in the component will be sorted. By default, sorting is performed on the database field specified in the dbField property, you can change the field to be used for sorting using the dbSortField property. You can define the type of sorting in the dbSortAsc property.
TabOrder	Integer	Indicates the position of the component in its parent's tab order. TabOrder is the order in which child components are visited when the user presses the Tab key.
TabStop	Boolean	Determines whether the user can tab to a control. Use the TabStop to allow or disallow access to the control using the Tab key.
Tag	Integer	Allows you to assign a number to a component for your own needs.
TagString	String	Allows you to assign a string to a component for your own needs.
Text	String	Contains a text string associated with the component.
TextHint	String	Specifies the text that is displayed as a text watermark in the edit box of the combo box control.
Visible	Boolean	Specifies whether the component appears onscreen.
Left	Integer	Specifies the horizontal coordinate of the left edge of a component relative to its parent.
Top	Integer	Specifies the vertical coordinate of the upper-left of a component relative to its parent.
Width	Integer	Specifies the horizontal size of the component in pixels.
Height	Integer	Specifies the vertical size of the component in pixels.

Methods

Method	Description
procedure dbAddRecord (id: integer; text: string)	Adds a record to the component and assigns it the specified id. The record will not be added to the database.
procedure dbEditRecord (id: integer; text: string)	Edits the record in the component with the specified id. The database record will not be edited.
procedure dbDeleteRecord (id: integer)	Deletes the record from the component with the specified id. The record will not be deleted from the database.
function dbGetFieldValue (FieldName: string): variant	The function allows you to get the value of the specified field from the database for the selected record in the component. If no record is selected in the component, the function returns Unassigned.
function dbIndexToID (index: integer): integer	The function allows you to get the id of a record by specifying its sequence number in the list.
procedure dbSQLExecute (sql: string)	The procedure allows you to fill a component with data from the database using an SQL query. The specified SQL query will be saved in the dbSQL property.
procedure dbUpdate	Forces the data in the component to be updated. Usually the component updates the data automatically if the data has been changed.
procedure Clear	Clears the contents of the component.
procedure DoOnChange	Forcibly executes the OnChange event if it was defined for a component.
procedure SetAllCheckBoxes (const Checked: boolean)	It makes sense if the MultiSelect property = True. Changes the state of the checkbox for each record.
procedure SetFocus	Gives the input focus to the component.

Events

Event	Description
OnChange	Occurs when the user changes the text displayed in the edit region.
OnClick	Occurs when the user clicks the component.
OnCloseUp	Occurs when the drop-down list closes up due to some user action.
OnDoubleClick	Occurs when the user double-clicks the left mouse button when the mouse pointer is over the component.
OnDropDown	Occurs when the drop-down list closes up due to some user action.
OnEnter	Occurs when a component receives the input focus.
OnExit	Occurs when the input focus shifts away from one component to another.
OnKeyDown	Occurs when a user presses any key while the form has focus.
OnKeyPress	Occurs when a key is pressed. Note that this procedure handles printable characters only.
OnKeyUp	Occurs when the user releases a key that was pressed.
OnMouseEnter	Occurs when the user moves the mouse into a component.
OnMouseLeave	Occurs when the user moves the mouse outside of a component.
OnDropFiles	Occurs when user tries to drag and drop a file from explorer to a form. More info.