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

# TColumn

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

Implements a display column for the TDBGrid control.

## Declaration

Source position: dbgrids.pas line 252

`type TColumn = class(TGridColumn)`
`protected`
`function CreateTitle; override;` |  | Creates the title used for the grid column.
`function GetDefaultAlignment; override;` |  | Gets the default alignment for the Field in the column definition.
`function GetDefaultDisplayFormat;` |  | Gets the default display format for the Field in a column.
`function GetDefaultValueChecked; override;` |  | Gets the default value for a check box in the Checked state as a String.
`function GetDefaultValueUnchecked; override;` |  | Gets the default String value for a check box in the UnChecked state.
`function GetDefaultVisible; override;` |  | Indicates if the Field for the column is Visible.
`function GetDisplayName; override;` |  | Gets the display name for the collection item.
`function GetDefaultReadOnly; override;` |  | Gets the default value for the ReadOnly property.
`function GetDefaultWidth; override;` |  | Gets the effective width for the column.
`function GetPickList; override;` |  | Gets the values in the pick list for the column.
`property IsAutomaticColumn: Boolean; [r]` |  | Indicates if the column was automatically added at run-time.
`property IsDesignColumn: Boolean; [r]` |  | Indicates if the column was added at design-time.
`procedure LinkField;` |  | Establishes a link between the FieldName and the Field in a Dataset.
`public`
`constructor Create(); override;` |  | Constructor for the TColumn instance.
`procedure Assign(); override;` |  | Stores properties from a persistent class in the current class instance.
`function IsDefault; override;` |  | Indicates if the column uses its default display format.
`property DesignIndex: Integer; [r]` |  | Order for the column in its collection at design-time.
`property Field: TField; [rw]` |  | Field in the Dataset associated with this Column.
`published`
`property FieldName: string; [rw]` |  | Name of the Field with data for the column.
`property DisplayFormat: string; [rws]` |  | The format to be used for display in this column.
`end;`

## Inheritance

`TColumn` |  | Implements a display column for the TDBGrid control.
`TGridColumn` |  | Implements a column definition used for tabular data in TCustomGrid.
`TCollectionItem`
?
`TObject`

## Description

TColumn is a TGridColumn descendant that represents a display column in a database grid control. TColumn extends the ancestor class to provide support for using TField for data access, display formatting, alignment, as well as use of check box and lookup list Fields. TColumn also implements support for features in TDBGrid like: automatic rows, and design-time vs run-time column ordering.

TColumn provides properties and methods needed to access and maintain the Dataset, Field, FieldName, and DisplayFormat for the column. TColumn provides overridden functions which implement facilities from the ancestor class.

TColumn instances can be created at run-time or design-time; properties are provided to indicate when the instance was created. The display order for columns need not correspond to the order of the Fields in the dataset, nor do all Fields in the dataset need to be represented by a display column.

TColumn instances are used as the collection item for the TDBGridColumns collection.

## See also

TDBGrid.Columns |  | Defines the dataset fields and their editing characteristics on the grid control.
TDBGridColumns |  | Implements a collection for columns in a database-aware grid.
TGridColumn |  | Implements a column definition used for tabular data in TCustomGrid.
TField
TDataset