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

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10 Appendix H Using ADO.NET 2.0 with Microsoft Access Databases Figure H.13 shows the result of dragging the tblEmploy table object to the MainForm, using the default control type for a table, and then sizing the control. In this case, the DataGridView control was sized by first setting its AutoSizeColumnsMode property to Fill. The Fill setting automatically adjusts the column widths so that all of the columns exactly fill the display area of the control. The control’s right border was then dragged to the desired width. BindingNavigator control DataGridView control AutoSizeColumnsMode property TableAdapter object BindingSource object DataSet object BindingNavigator object FIGURE H.13 Result of dragging the tblEmploy table object to the form in the Morgan Industries application Besides adding a DataGridView control to the form, the computer also adds a BindingNavigator control. When an application is running, the BindingNavigator control allows you to move from one record to the next in the dataset. It also allows you to add and delete a record, as well as save any changes made to the dataset. In addition, the computer places four objects in the component tray: a DataSet, a BindingSource, a TableAdapter, and a BindingNavigator. As you learned in Chapter 2, the component tray stores objects that do not appear in the user interface when an application is running. An exception to this is the BindingNavigator object, which appears as the BindingNavigator control during both design time and run time. Figure H.14 illustrates the relationships among the database, the objects in the component tray, and the controls on the form. Appendix H C5779 39147 Page 10 07/10/06--JHR
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.
Page 1 and 2: H Using ADO.NET 2.0 with Microsoft
Page 3 and 4: Database Terminology 3 Notice that
Page 5 and 6: Connecting a Database to an Applica
Page 7 and 8: Connecting a Database to an Applica
Page 9: Binding the Objects in a Dataset 9
Page 13 and 14: Binding the Objects in a Dataset 13
Page 15 and 16: Binding the Objects in a Dataset 15
Page 17 and 18: Accessing the Records in a Dataset
Page 19 and 20: Dataset Designer 19 You can use the
Page 21 and 22: Dataset Designer 21 Appendix H C577
Page 23 and 24: Dataset Designer 23 3. In the Choos
Page 25 and 26: Dataset Designer 25 Used by the WHE
Page 27 and 28: Dataset Designer 27 The user can ru
Page 29 and 30: Programming Tutorial 29 TOE Chart:
Page 31 and 32: Programming Tutorial 31 6. Click th
Page 33 and 34: Programming Tutorial 33 Appendix H
Page 35 and 36: Programming Tutorial 35 5. Click th
Page 37 and 38: Programming Tutorial 37 Option Expl
Page 39 and 40: Programming Example 39 TOE Chart: T
Page 41 and 42: Quick Review 41 Private Sub MainFor
Page 43 and 44: Self-Check Questions and Answers 43
Page 45 and 46: Review Questions 45 3. A group of r
Page 47 and 48: Computer Exercises 47 3. Write a SE
Page 49 and 50: Case Projects 49 c. Allow the user

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