It is also possible to be in a mixed mode, where you bind to a data source but also add one or more unbound columns to the DataGridView object.

Every version of Microsoft Visual Studio has had a data grid control that is meant to provide easy browse and change capability with minimal effort by the developer.

This chapter will examine the Windows data grid control, called the DataGridView, which is available in Visual Studio 2005; the next chapter will examine the Web data grid control, called the GridView.

Understanding the DataGridView Control The DataGridView control is used on Windows Forms applications to display data in a tabular, rows-and-columns format.

Earlier grid controls were difficult to customize without diving deep into Windows handles and messages, but the DataGridView object exposes more than 160 events to make it much simpler to access the key area of the grid.

The basic structure of the DataGridView object is shown in Figure 7-1.

The DataGridView object consists of collections of rows and columns.

The Rows property provides a collection of DataGridViewRow objects.

Each DataGridViewRow object contains a Cells collection, which is a collection of objects that derive from the DataGridViewCell class.

The Columns property provides a collection of objects that derive from the DataGridViewColumn class.

Although the DataGridViewRow object holds the collection of cells, each DataGridViewColumn provides an instance of a specific cell that is used as a template.

The DataGridViewRow object can access the cell template to create clones of the correct cell type.

With the exception of the header types, the class hierarchy of the DataGridViewColumn class is similar to that of the DataGridViewCell class.

You dont define cell types for your DataGridView object you define columns, and each column object supplies a cell object to the row; the row uses the cells as templates for creating the proper cell types for the row.

Figure 7-2: The DataGridViewCell class hierarchy Formatting with Styles You use styles to format the DataGridView object.

You can assign styles to individual cells, rows, or columns or to the whole DataGridView object.

The effective style of a cell is derived by evaluating from the least specific style (the DataGridView object) to the most specific style (the cell style).

The style properties are additive, which means that when the BackColor property is set to red on the DataGridView object and the Font is set to Arial on the cell, the cell renders with the Arial font and a red background.

When there is a conflict, such as different BackColor settings, the most specific setting prevails.

You can use the CellFormatting event to control the style programmatically.

The benefit is that you can apply business rules to specify whether a cell should stand out from other cells (for example, making the negative quantity on hand number red, but only when the inventory item sells more than one item per month).

DataGridView Modes of Operation The DataGridView supports three modes of operation: bound, unbound, and virtual.

You are in bound mode when you bind, or connect, the DataGridView object to a data source.

You are in unbound mode when you simply populate the row data programmatically.

Hierarchical Datagridviewbuttoncolumn