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

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18 Appendix H Using ADO.NET 2.0 with Microsoft Access Databases Examples TblEmployBindingSource.MoveFirst() moves the record pointer to the first record in the dataset TblEmployBindingSource.MoveLast() moves the record pointer to the last record in the dataset TblEmployBindingSource.MoveNext() moves the record pointer to the next record in the dataset TblEmployBindingSource.MovePrevious() moves the record pointer to the previous record in the dataset Moves the record pointer to the next record in the dataset Moves the record pointer to the previous record in the dataset Visual Basic code FIGURE H.22 When the Next button in the Morgan Industries application is clicked, its Click event procedure should move the record pointer to the next record in the dataset. Similarly, when the Previous button is clicked, its Click event procedure should move the record pointer to the previous record in the dataset. You can use the TblEmployBindingSource object’s MoveNext and MovePrevious methods to code the procedures, as shown in Figure H.23. Private Sub nextButton_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles nextButton.Click TblEmployBindingSource.MoveNext() End Sub Private Sub previousButton_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles previousButton.Click TblEmployBindingSource.MovePrevious() End Sub FIGURE H.23 How to use the BindingSource object’s Move methods Code entered in the Next and Previous buttons’ Click event procedures Appendix H C5779 39147 Page 18 07/10/06--JHR DATASET DESIGNER As you learned earlier, data stored in a relational database can be displayed in any order. For example, you can arrange the data contained in the Employees database by employee number, pay rate, status, and so on. A relational database also allows you to control the amount of information you want to view at a time. You can view all of the information in the Employees database, or you can view only the employee numbers and corresponding pay rates. You also can choose to view only the records for the part-time employees.
Dataset Designer 19 You can use the DataSet Designer to indicate the order in which you want data displayed, and also to specify the fields and records you want to view from the database. Figure H.24 shows various ways of opening the DataSet Designer, and Figure H.25 shows the DataSet Designer open in the IDE. HOW TO… Open the DataSet Designer • Right-click the Data Sources window, then click Edit DataSet with Designer. • In the Solution Explorer window, right-click the name of the schema file, which has an .xsd extension, then click View Designer. • Right-click the TableAdapter object in the component tray, then click Edit Queries in DataSet Designer. Appendix H C5779 39147 Page 19 07/10/06--JHR DataSet Designer Name assigned to the schema file Names of the table and fields in the dataset Name of the TableAdapter object Query FIGURE H.24 FIGURE H.25 How to open the DataSet Designer DataSet Designer The key icon in Figure H.25 indicates that the Emp_Number field is the primary field in the tblEmploy table. Notice that the Solution Explorer window shown in Figure H.25 contains a file named EmployeesDataSet.xsd. The filename also appears on the tab in the DataSet Designer. The .xsd extension on the filename indicates that the file is an XML schema definition file. XML, which stands for Extensible Markup Language, is a text-based language used to store and share data between applications and across networks and the Internet. An XML schema definition file defines the tables and fields that make up the dataset. The .xsd file is added to the Solution Explorer window when you connect a database to an application. The DataSet Designer in Figure H.25 shows the name of the table object included in the EmployeesDataSet. It also lists the names of the seven field objects included in the dataset. In addition, it shows the name of the application’s TableAdapter object, which connects the dataset to its underlying database. Every TableAdapter object contains one or more queries, which are listed below the TableAdapter object’s name in the DataSet Designer. A query specifies the fields and records to retrieve from the database, as well as the order in which to arrange the fields and records. As Figure H.25 indicates, the TableAdapter object in the
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
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Page 17: Accessing the Records in a Dataset
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
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Page 35 and 36: Programming Tutorial 35 5. Click th
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Page 39 and 40: Programming Example 39 TOE Chart: T
Page 41 and 42: Quick Review 41 Private Sub MainFor
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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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