Creating a Custom Dataset or
SQLDataSource
In both Windows Forms and ASP.NET, once you’ve
laid out your form with the previously mentioned controls,
you’ll see the context menu for the grid in the grid’s
upper right corner. On this menu, you’ll see a Choose
Data Source dropdown list. For the Windows Forms
application, you’ll find that when you open this list for
a new project, an Add Project Data Source link will appear
near the bottom. In ASP.NET, opening the same
Choose Data Source option reveals a simple dropdown
list with the option to create a new data source.
In either case, you’ll enter a wizard screen that lets you
specify the underlying source of your data—a database—
then lets you to build a connection string for that
data source. These are fairly common steps, so I won’t
go into detail. In both cases, the final step in this process
of defining your data objects is to automatically add the
connection information to your associated .config file.
Having created your data source, you now need
to define your data objects. Figure 1 shows the next
Windows Forms screen. I’ve expanded the Stored
Procedures section. The wizard can’t associate all the
stored procedures into a single table adapter, so after
the wizard finishes, I’ll need to complete this step
for my Windows Forms solution. At this point, I can
finish the wizard, which will create the XML Schema
Definition (XSD) describing my data set, add this element
to my project, and let me edit the definition of
my table adapter.
The ASP.NET wizard is a bit more involved. Its first
screen lets you either select one or more tables or choose
the Specify a custom SQL statement or stored procedure
option. Selecting the custom option, you’ll then press
Next, at which point the wizard lets you specify either
a custom SQL statement or a stored procedure for SELECT,
UPDATE, INSERT, and DELETE.
After you fill in all four stored procedures and
press Next, you’ll map the parameter for your Select
statement to a field outside your data grid. On the
assumption that this parameter needs to come from
somewhere, the wizard lets you map either a query
string value or, in this case, a form value. As I described
earlier, there will be a text box on the form, so
this control is mapped as the source of this parameter.
(If the text box is empty, the system provides a default
value of ALFKI—the customer ID for the first customer
in the Northwind sample database.)
Once you’re satisfied with your settings on this
screen, the final screen lets you execute a test run of
your query statement. Unlike the Windows Forms solution,
the ASP.NET solution updates your default.
aspx page. The default.aspx page will use the data
definition embedded in the page to make the calls to
the database. Now that we’ve finished setting the data
source for ASP.NET, let’s return to Windows Forms
and set up a basic data-bound grid.
Windows Forms Data Binding
As I mentioned earlier, the Windows Forms wizard
doesn’t really understand how to map additional
stored procedures to your data adapter. As you’ll see,
this shortcoming has implications beyond the wizard.
First, a quick review: By now, you’ve created a new
Windows Application project, similar to the WinForm
DataBinding.zip sample available for download at www.sqlmag.com, InstantDoc ID 97104. Your application
would have automatically generated a Form 1,
and you’ll have used the design to lay out your form
similar to what Figure 2 shows.
Notice that in addition to showing the form, the
figure also shows the grid control’s context menu,
from which you defined your data source. Also, note
that the associated options for Adding, Editing, Deleting,
and Sorting are selected. This control’s context
menu is quite different from that of the ASP.NET
GridView control (discussed later).
Finally, by clicking on the Edit Columns option,
you can change the default width of the various columns,
map in different display headers, make key
columns Read Only, and even make certain columns
such as Company ID invisible so that they won’t appear
in your UI.
After you finish customizing the DataGridView
control from the context menu, it’s time to review the
capabilities of your custom data set. To do so, review
your solution in the solution explorer and locate the
.xsd file, which was added as part of the wizard process
that created your data object. The sample code
has one called dataset1.xsd, and double-clicking this
file opens a graphical representation of the newly created
typed dataset and its associated table adapter.
Working with a table adapter is important because it’s
the adapter that lets you map in your database actions
as stored procedures. Right-click the table adapter,
and select Configure from the context menu.
The Configure option opens the screen that Figure
3 shows. This wizard is designed to let you group
related stored procedures onto a given table adapter.
After you fill in your stored procedures in the wizard,
you’ll proceed to Figure 4, which shows the default
methods to be created for your table adapter.
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