This step-by-step article describes how to create a Windows
form that displays a parent (or master) record and all the related child (or
detail) records by using the Northwind Customers and Orders tables. This
article also describes the
CurrencyManager object and its purpose.
In this article, the parent
record information appears in
TextBox controls, and the child record information appears in a
DataGrid control. The project that you create in this article also
contains
Button controls so that you can browse through the
records.
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Requirements
The following list outlines the recommended hardware, software,
network infrastructure, and service packs that you need:
| • | Microsoft Windows 2000 Professional, Windows 2000 Server,
Windows 2000 Advanced Server, or Windows NT 4.0 Server |
| • | Microsoft SQL Server 7.0 or 2000, or Microsoft Data Engine
(MSDE) with the Northwind sample database installed |
| • | Microsoft Visual Studio .NET 2003 or Microsoft Visual
Studio 2005 |
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Understand the CurrencyManager object
Make sure that you understand the function of the
CurrencyManager object to help you follow the sample in this article. Any data
source that you bind to a Windows Forms control contains an associated
CurrencyManager object. The
CurrencyManager object monitors the position and otherwise supervises bindings to
that data source. The form contains a
CurrencyManager object for each discrete data source to which you are binding. If
all of the controls on the form bind to a single source (for example, if
several
TextBox controls are bound to the same data table), all the controls
share the same
CurrencyManager object. When the controls on the form are bound to different
sources, the form contains multiple
CurrencyManager objects. Each of these
CurrencyManager objects tracks the record or the data element that the controls
are using.
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Create the project
To create the project that demonstrates the functionality of the
CurrencyManager object, follow these steps:
| 1. | Start Visual Studio .NET 2003 or Visual Studio 2005, and
then create a new Microsoft Visual C++ Windows Forms Application (.NET)
project.
Note In Visual Studio 2005, create a new Microsoft Visual C++ Windows
Forms Application project. |
| 2. | Add three TextBox controls, five
Button controls, and one DataGrid control to
the form. |
| 3. | Change the Text properties of the
Button controls to Fill,
First, Next,
Previous, and Last. |
| 4. | Switch to Code view, and add the following statement to
the top of the Code window:using namespace System::Data::SqlClient; |
| 5. | Add the following member variable to the Form1 class after the private statements:CurrencyManager * cm; |
| 6. | Switch to Form view, and then double-click Fill. Add the following code to the Click event:
{// Get the data.
SqlConnection * con = new SqlConnection("server=YourServer;
uid=YourUserID;pwd=YourPassword;database=northwind");
SqlDataAdapter * daCust = new SqlDataAdapter("Select * from Customers", con);
SqlDataAdapter * daOrders = new SqlDataAdapter("Select * from Orders",con);
DataSet * ds=new DataSet();
daCust->Fill(ds,"Cust");
daOrders->Fill(ds,"Orders");
ds->Relations->Add("CustOrd",ds->Tables->get_Item("Cust")->Columns->get_Item("CustomerID"),
ds->Tables->get_Item("Orders")->Columns->get_Item("CustomerID"));
//
//Bind the controls.
//
textBox1->DataBindings->Add("Text", ds->Tables->get_Item("Cust"),"CustomerID");
textBox2->DataBindings->Add("Text", ds->Tables->get_Item("Cust"),"CompanyName");
textBox3->DataBindings->Add("Text", ds->Tables->get_Item("Cust"),"ContactName");
dataGrid1->DataSource=ds->Tables->get_Item("Cust");
dataGrid1->DataMember="CustOrd";
//
//Initialize the CurrencyManager.
//
try{
cm=__try_cast<CurrencyManager *>(this->BindingContext->get_Item(ds->Tables->get_Item("Cust")));
}
catch(Exception * ex)
{
MessageBox::Show(ex->get_Message(),S"Exception");
}}
| a. | Click Project, and then click
<ProjectName> Properties.
Note <ProjectName> is a placeholder
for the name of the project. | | b. | Expand Configuration Properties, and
then click General. | | c. | Click to select Common Language Runtime
Support, Old Syntax (/clr:oldSyntax) in the Common Language
Runtime support project setting in the right pane, click
Apply, and then click OK. |
For more information about the common language runtime
support compiler option, visit the following Microsoft Web site:These
steps apply to the whole article. |
| 7. | Modify the connection string as is appropriate for your
environment. |
| 8. | Double-click First, and then add the
following code to the Click event:
{if((cm!=NULL)&(cm->Count>0))
cm->Position=0;}
|
| 9. | Double-click Next, and then add the
following code to the Click event:
{if((cm!=NULL)&(cm->Count>0)&(cm->Position<cm->Count-1))
cm->Position +=1;}
|
| 10. | Double-click Previous, and then add the
following code to the Click event:
{if((cm!=NULL)&(cm->Count>0)&(cm->Position>0))
cm->Position -=1;}
|
| 11. | Double-click Last, and then add the
following code to the Click event:
{if((cm!=NULL)& (cm->Count>0))
cm->Position=cm->Count;}
|
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Test the application
| 1. | Press F5 to compile and to run the
application. Notice that the form is initially empty. |
| 2. | Click Fill to load and to bind the data,
and then use the navigation buttons to move through the data. |
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For more information, visit the following Microsoft
Developer Network (MSDN) Web site:
For more information about the
CurrencyManager object, refer to the Visual Studio .NET Help
documentation.
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