ADO.NET in a Nutshell

Retrieving Updated Values from the Data Source

There are three techniques that can retrieve updated data from the data source.

The first technique is to use a batch query to return the new value using a query after the update command has executed. Example 15-3 demonstrates this for an AutoIncrement column by creating a batch insert statement containing the statements:

    "SET @OrderID = Scope_Identity();" +

    "SELECT @OrderID OrderID;";

If the row also contains a timestamp column named rowversion, the following code can be used with the insert statement to retrieve the new timestamp value:

    "SET @OrderID=Scope_Identity();" + 

    "SELECT @OrderID OrderId, rowversion WHERE OrderID = @OrderID;";

This technique requires that the UpdatedRowSource property update commands be set to either Both or FirstReturnedRecord.

The second technique uses output parameters to retrieve updated data. Example 15-3 demonstrates the use of this method with an AutoIncrement column by creating an output parameter for the OrderID on the InsertCommand:

params.Add("@OrderID", SqlDbType.Int, 0, "OrderID");

params.Direction = ParameterDirection.Output;

This technique requires that the UpdatedRowSource property for the update command be set to either Both or OutputParameters.

The third technique handles the DataAdapter RowUpdated event. An event handler is first attached to the data adapter:

da.RowUpdated += new SqlRowUpdateEventHandler(da_RowUpdated);

The event handler retrieves the new AutoIncrement value and stores it in the ...