HUsing ADO.NET 2.0 with Microsoft Access Databases - Cengage ...

Binding the Objects in a Dataset 11
DataSet
TableAdapter
BindingSource
Database
Bound controls
on the form
Appendix H C5779 39147 Page 11 07/10/06--JHR
The DataSet, BindingSource,
and TableAdapter objects, as
well as the Timer control you
learned about in Chapter 2,
are examples of objects that
appear in the component tray
during design time, but are not
visible during run time.
FIGURE H.14
Illustration of the relationships among the database, the
objects in the component tray, and the controls on the form
The TableAdapter object connects the database to the DataSet object,
which stores the information you want to access from the database. The
TableAdapter is responsible for retrieving the appropriate information from
the database and storing it in the DataSet. It also is responsible for saving to the
database any changes made to the data contained in the DataSet.
The BindingSource object provides the connection between the DataSet
object and the bound controls on the form. For example, the
TblEmployBindingSource object (shown earlier in Figure H.13) connects the
EmployeesDataSet object to two bound controls: the DataGridView control and
the BindingNavigator control. The BindingSource object allows the DataGridView
control to display the data contained in the dataset. It also allows the
BindingNavigator control to access the records stored in the dataset.
If a table object’s control type is changed from DataGridView to Details, the
computer automatically provides the appropriate controls (such as text boxes,
labels, and so on) when you drag the table object to the form. It also adds the
BindingNavigator control to the form, and adds the DataSet, BindingSource,
TableAdapter, and BindingNavigator objects to the component tray. The appropriate
controls and objects are also automatically included when you drag a field
object to an empty area on the form.
When a table or field object is dragged to the form, the computer not only
adds the appropriate controls and objects to the application, but it also enters
some code in the Code Editor window. Figure H.15 shows the code that is automatically
entered in the Code Editor window when the tblEmploy object is
dragged to the form.