Programming Visual Basic .NET, Second Edition

Changing Database Records

So far, you’ve retrieved data from a database, but you haven’t manipulated its records in any way. Using ADO.NET, it is of course possible to add records, change an existing record, or delete a record altogether.

In a typical implementation, you might work your way through the following steps:

1. Fill the tables for your DataSet using a stored procedure or SQL.

2. Display the data in various DataTable objects within your DataSet by either binding to a control or looping through the rows in the tables.

3. Change data in individual DataTable objects by adding, modifying, or deleting DataRow objects.

4. Invoke the GetChanges( ) method to create a second DataSet that features only the changes to the data.

5. Check for errors in the second newly created DataSet by examining the HasErrors property. If there are errors, check the HasErrors property of each DataTable in the DataSet. If the table has errors, invoke the GetErrors( ) method of the DataTable and get back an array of DataRow objects with errors. On each row you can examine the RowError property for specific information about the error, which you can then resolve.

6. Merge the second DataSet with the first.

7. Call the Update( ) method on the DataAdapter object and pass in the merged DataSet.

8. Invoke the AcceptChanges( ) method on the DataSet, or invoke RejectChanges( ) to cancel the changes.

This process gives you very fine control over the update to your data as well as an opportunity to fix any data that would otherwise ...