Programming .NET Windows Applications

Command Builder

In the previous section, you painstakingly created the Update, Insert, and Delete commands. You first created stored procedures, and then you created Command objects for each procedure, passing in the necessary parameters. The .NET Framework does a lot of this work for you, if the update, insert, and delete commands are simple enough.

The framework provides a Command Builder (SqlCommandBuilder and OleDbCommandBuilder) to generate the necessary Delete, Update, and Insert commands without your writing stored procedures. To take advantage of these objects, the following conditions must be met:

• The rows in the table you generate must come from a single table (or view) in the database.

• The table must have a primary key or a field with values guaranteed to be unique.

• The unique value column must be returned by the query used to fill the DataSet (the select command).

• The name of the table must not have spaces, periods, quotation marks, or other special characters.

To see how using the Command Builder classes simplifies the task when these conditions are met, you'll modify the program to build the DataSet only from the Bugs table. Your user interface will be much simpler because you'll use a simple Select statement: "Select * from Bugs".

Create a new application called UpdatingDataSetsCommandBuilder with a form like that shown in Figure 20-10. Add three buttons and a DataGrid, as described in Table 20-3.

Figure 20-10. Updating DataSets Command Builder form

Table 20-3. Controls ...