ADO.NET Cookbook

4.3. Getting an AutoNumber Value from Microsoft Access

Problem

If you add a row into a Microsoft Access table that has an AutoNumber column, the value assigned to the column in the DataTable is replaced by a value generated by the database. You need to retrieve the new value to keep the DataTable synchronized with the database.

Solution

Use the RowUpdated event handler to retrieve the new AutoNumber value generated by Microsoft Access.

The sample code contains three event handlers:

Form.Load

Sets up the sample by creating a DataTable and programmatically defining the schema to match the Categories table in Northwind. The AutoIncrementSeed and AutoIncrementStep property values are both set to -1 for the AutoIncrement primary key column, the CategoryID. A DataAdapter is created and used to fill the DataTable. The insert command and its parameters are defined for the DataAdapter so that new rows can be added to the data source. An event handler is defined for the RowUpdated event of the DataAdapter to retrieve the AutoNumber value generated for the CategoryID by Access. The default view of the table is bound to the data grid on the form.

Add Button.Click

Creates a new row in the Categories DataTable using the entered CategoryName and Description values and the automatically generated CategoryID field. The Update( ) method of the DataAdapter is used to insert the row into the data source and the DataAdapter RowUpdated event handler synchronizes the AutoNumber value generated by Access to ...