The main part of the wizard's work is in configuring the four data command objects that the adapter uses to pass data to and from the database. These include the SelectCommand object, and optionally, the UpdateCommand, InsertCommand, and DeleteCommand objects. Each of these objects contains either a SQL statement or the name of a stored procedure used to read and write data. The properties of each of these commands (especially the CommandText property) are set according to choices you make in the wizard.

The wizard allows you to use either SQL statements or stored procedures for the commands. It gives you these options:

• Use SQL statements. You can specify a Select statement, and if you choose to create them, the wizard builds corresponding Update, Insert, and Delete statements based on what you have included in the Select statement. The Update and Insert statements include parameters to pass new values. The Update, Insert, and Delete statements include parameters in a WHERE clause to locate the correct record in the database.

• Create new stored procedures. This option is similar to using a statement, except that the wizard generates stored procedures instead of statements. Because stored procedures can be faster than SQL statements, you might choose this option for performance. In this option, the wizard generates stored procedures for all four commands (again based on what you specify in the Select command). You can choose to have the new stored procedures written to your database. If you don't, you can still capture the SQL script that the wizard would use to create the stored procedures, and you can execute the script yourself later.

• Use existing stored procedures. In this option, you pick stored procedures for each of the four commands. The wizard displays the names and details of stored procedures that it can find in the database. This option is useful if you already have stored procedures that perform the four database operations.

The following are steps that you often perform after the Data Adapter Configuration Wizard has finished:

• Add more data adapters. The wizard creates one data adapter. Typically, each data adapter is used to read and write data to a single data table. If you intend to use a dataset that contains multiple tables, you will probably want to add more data adapter to your form or component. Each time you add a data adapter from the Toolbox, you rerun the wizard to configure that particular data adapter.

• Change an adapter's table mappings. By default, the adapter assumes that it will be reading and writing to tables and columns with the same names. However, you might be using the adapter to read from a database that uses one name into a dataset that uses different names. Or you might be reading more columns from the database than you need in the dataset. For more information on how to change these settings, see How to: Map Data-Source Columns to Dataset Data-Table Columns.

• Preview the data that the adapter will fill into the dataset. For more information, see How to: Preview Data-Adapter Results.

• Add logic to fill the dataset. To use the data adapter to fill a dataset, you call the adapter's Fill method. This executes the command in the adapter's SelectCommand object and fills the results into the dataset. For more information, see Populating a DataSet from a DataAdapter (ADO.NET).