Beginning Visual C++ 2005 (2006) [eng]-1

Accessing Data Sources in a Windows Forms Application

Summar y

This has been a brief introduction to the capabilities you have for accessing data sources in a Windows Forms application. There’s a great deal more you can do, but you should find that as you now have a good idea of how you use the design capability to assemble controls on a form and how the controls involved in data access work together. You’ll have few problems getting into other areas by yourself.

The key points you have learned about in this chapter include:

A data source can be a relational database, a Web service, or an object.

A class derived from the System::Data::DataSet class is used to encapsulate a data source, and a class derived from the System::Data::DataTable class table encapsulates a table in a data source.

A row of data in a DataTable object is represented by an object of type System::Data::DataRow, and the schema for a column is described by an object of type

System::Data::DataColumn.

A connection to a data source and the commands to access the data are encapsulated in a component called a table adapter.

You use a DataGridView control on a form to display data in the form of a rectangular grid.

You can bind a DataGridView control to a data source to display the contents of a table. You can also use a DataGridView control in unbound mode to display data originating in your program.

You can customize a DataGridView control to modify how rows, columns, headers and individual cells are displayed.

A BindingSource component provides an interface between a data source and controls on a form. A BindingSource component can link the columns in a table to individual controls on a form, or it can link the contents of a table to a DataGridView control.

A BindingNavigator control provides a toolbar for navigating data that you access via a

BindingSource component.

Exercises

You can download the source code for the examples in the book and the solutions to the following exercises from http://www.wrox.com.

1.Modify Ex22_04 so that the column headers are displayed in a 12-point italic font.

2.Modify Ex22_05 so the columns are wide enough to accommodate the text in each cell.

3.Modify Ex22_05 so that alternate rows of data on each tab page appear shaded.

4.Create a Windows Forms application that displays the Suppliers table from the Northwind database.

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Appendix A

C++/CLI Keywords

The C++/CLI language specification defines the following keywords in addition to those defined for ISO/ANSI C++:

Note that the word pairs are keywords, not necessarily the individual words; for example, for each is a keyword, but each is not.

The C++/CLI language also defines a number of identifiers that are not keywords but have a contextsensitive meaning in some circumstances. These are:

In principle you can still use these identifiers as names in your code because the context determines when they have special significance, but I recommend that you treat them as keywords and do not use them for other purposes. In that way you avoid any possibility for confusion on the part of someone else who may be reading your code.

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ASCII Codes

Table continued on following page

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Appendix B

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ASCII Codes

The Unicode codes that have the same numerical code values as the ASCII codes in the table represent the same characters. You’ll find comprehensive information on the Unicode character coding system at http://www.unicode.org.

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