ADO.NET in a Nutshell

Updating the Data Source

The Update( ) method can submit DataSet changes back to the data source. It uses the statements in the DeleteCommand, InsertCommand, and UpdateCommand objects to attempt to update the data source with records that have been deleted, inserted, or updated in the DataSet. Each row is updated individually and not as part of a batch process. Furthermore, the order in which the rows are processed is determined by the indexes on the DataTable and not by the update type. Figure 14-2 illustrates how the DataAdapter is used both to reconcile changed data in the DataSet with the data source using the Update() method and to retrieve data from the data source using the Fill() method.

Figure 14-2. Retrieving and updating data using the DataAdapter

The delete, insert, and update statements can be automatically generated using the CommandBuilder object, but this is probably not the best approach for production systems. The CommandBuilder object is discussed in more detail in Chapter 15. Alternatively, custom update logic can be used where the DeleteCommand, InsertCommand, and UpdateCommand are each defined. Compared with using the CommandBuilder, custom logic can significantly improve performance and can implement solutions to complex updating and conflict-resolution scenarios. Custom update logic is also examined in detail in Chapter 15.

The following example demonstrates ...