This article describes how to search for data in a Microsoft
Windows Forms
DataGrid control and how to synchronize the grid with the search results.
In this sample, you programmatically retrieve data into a
DataView class and then bind the
DataView to the
DataGrid. You can then type criteria in a text box and then click
Find to search for the record and to move the record pointer
to the correct row in the
DataGrid control. This sample also indicates if the search cannot locate a
record.
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Requirements
This
article assumes that you are familiar with the following topics:
| • | Microsoft ADO.NET |
| • | Microsoft Windows Forms controls |
The following list outlines the recommended hardware, software,
network infrastructure, and service packs that you need:
| • | Microsoft Visual C++ .NET |
| • | Microsoft Visual C++ 2005 |
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Description of the technique
Set the sort order and find the records
To use the
DataView.Find method to find a record, you must set the sort order. In this
example, when you click the column header in the
DataGrid control, the
DataGrid control sets the sort order for you. The sample uses syntax to
set the sort order programmatically. This syntax is similar to the SQL ORDER BY
syntax.
//Examples: Set the default sort order.
tblAuthors->DefaultView->Sort = "au_id";
tblAuthors->DefaultView->Sort = "au_id DESC";
tblAuthors->DefaultView->Sort = "f_name,l_name"; // multicolumn sort/find
You can also change the sort order visually by clicking the column
headers in the
DataGrid control. When you click
Find, you use that
column sort order to perform your search.
Note The arrow in the column header indicates the current sort order.
The direction of the arrow indicates whether the order is ascending or
descending.
Retrieve the
current sort order programmatically
To retrieve the current sort order and to update the Label text,
read the
DataView.Sort property as follows.
lblFind->Text = System::String::Concat("Enter Search Criteria ",dv->Sort); //Used in this example to set the label.Position the record pointer in a DataGrid control
In this sample, you use the
DataView.Find method to retrieve the record position and to update the
CurrencyManager object. This action synchronizes the record pointer in the
DataGrid control. If you want to select the row, you can use the
DataGrid.Select method.
This sample uses the
CurrencyManager object to work with currency. You can also use the
BindingManagerBase class. The
BindingManagerBase class is the base class for the
CurrencyManager object. All data binding is performed through
DataView classes. To synchronize your controls and the
CurrencyManager object, the controls must be bound to the same
DataView class.
// Search for the record in the DefaultView.
// If the record is found, move the record pointer to the correct record in the grid.
int i;
i = dv->Find(txtFind->Text);// Locates record in DefaultView.
// Does not move the record pointer or the CurrencyManager object.
if(i > dv->Table->Rows->Count || i < 0)
MessageBox::Show("Record Not found");
else
CM->Position = i; // Synchronizes the CurrencyManager object and the record pointer.Back to the top
Create the sample
| 1. | Start Microsoft Visual Studio .NET 2003 or Microsoft Visual
Studio 2005. |
| 2. | On the File menu, point to
New, and then click Project. |
| 3. | Under Project Types, click Visual
C++ Projects.
Note In Visual Studio 2005, click Visual C++ under
Project Types. |
| 4. | Under Templates, click Windows
Forms Application (.NET).
Note In Visual Studio 2005, click Windows Forms
Application under Templates. |
| 5. | In the Name box, type
815679, and then click OK. By default,
the Form1 form is created. |
| 6. | Add a DataGrid control, a Button control, a Label control, and a TextBox control to the form. |
| 7. | In the Properties window, set the properties for these
controls as follows:
| • | Form control
Name: frmFind
Size: 800, 520
Text: Search Form | | • | Label control
Name: lblFind
AutoSize: True
Location: 168, 456
Text: Enter Search Criteria au_id | | • | TextBox control
Name: txtFind
Location: 328, 456
Size: 216, 20
Text: Button | | • | Button control
Name: btnFind
Location: 560, 456
Size: 75, 32
Text: Find | | • | DataGrid control
Name: grdFind
Location: 16, 8
Size: 760,432 |
|
| 8. | Use the using directive on the System.Data.SqlClient namespace so that you do not have to qualify declarations for
this namespace later in your code. You must use this statement before class frmFind.using namespace System::Data::SqlClient; |
| 9. | Add the following variable declarations to the frmFind class before the existing code.SqlConnection* conn;
SqlDataAdapter* daAuthors;
DataSet* ds;
DataView* dv;
CurrencyManager* CM; | 1. | Click Project, and then click ProjectName Properties.
Note ProjectName represents the name of the project. | | 2. | Expand Configuration Properties, and
then click General. | | 3. | Click to select Common Language Runtime
Support, Old Syntax (/clr:oldSyntax) in the Common Language
Runtime support project setting on the right pane, click
Apply, and then click OK. |
For more information about the common language runtime
support compiler options, visit the following Microsoft Web site:These steps apply to the whole article. |
| 10. | Add the following code to the frmFind_Load event.
Note You must modify the connection string to connect correctly to
your computer that is running Microsoft SQL Server.//Modify this string to connect correctly to your computer that is running SQL Server.
conn = new SqlConnection("server=<YourServerName>;uid=<YourUserId>;pwd=<YourPassword>;database=pubs");
daAuthors = new SqlDataAdapter("Select * From Authors", conn);
ds = new DataSet();
//Retrieve data from the Authors table.
daAuthors->Fill(ds, "Authors");
dv = new DataView(ds->Tables->get_Item("Authors"));
//Bind the data to the DataGrid control.
grdFind->DataSource = dv;
//Set the default sort order.
dv->Sort = "au_id";
// Initialize CurrencyManager to hold an instance of the form's CurrencyManager object.
CM = __try_cast<System::Windows::Forms::CurrencyManager *>(grdFind->BindingContext->get_Item(dv));
//Register the ListChanged event of the DataView class.
dv->ListChanged += new System::ComponentModel::ListChangedEventHandler(this, dv_ListChangedEvent); |
| 11. | Add the following code to the btnFind_Click event handler.// Verify that the user typed text to search for.
if(txtFind->Text->Equals(String::Empty))
{
MessageBox::Show("Enter some criteria to find.");
txtFind->Focus();
}
else
{
// Search for the record in the DefaultView.
// If the record is found, move the record pointer to the correct record in the grid.
int i;
i = dv->Find(txtFind->Text);// Locates record in DefaultView.
if(i > dv->Table->Rows->Count || i < 0)
MessageBox::Show("Record Not found");
else
CM->Position = i; // Synchronizes the CurrencyManager object and the record pointer.
} |
| 12. | Add the dv_ListChangedEvent event handler.private: void dv_ListChangedEvent(Object* sender, System::ComponentModel::ListChangedEventArgs* args)
{
// This code permits the Label2.Text to be displayed correctly.
if(dv->Sort->Substring((dv->Sort->Length - 4), 4) == "DESC")
lblFind->set_Text(System::String::Concat("Enter Search Criteria ",dv->Sort->Substring(0, dv->Sort->Length - 5)));
else
lblFind->set_Text(System::String::Concat("Enter Search Criteria ",dv->Sort));
} |
| 13. | Open the source file Form1.cpp, and then
modify the code of the Application::Run method to reflect the new name of the form.Application::Run(new frmFind());
|
| 14. | Press CTRL+SHIFT+S to save the project. |
| 15. | Press CTRL+SHIFT+B to build the solution. |
| 16. | Press CTRL+F5 to run the project. |
| 17. | Click the DataGrid header to change the
sort order, type some search criteria in the text box, and then click
Find. Notice that the record pointer is positioned correctly
in the DataGrid control. |
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For more information about ADO.NET, about the
DataSet object, about the methods in this article, and about SQL Server,
visit the following Microsoft Developer Network (MSDN) Web sites:
For additional information, click the following
article numbers to view the articles in the Microsoft Knowledge Base:
168336 (http://kbalertz.com/Feedback.aspx?kbNumber=168336/)
HOWTO: Open ADO Connection and Recordset objects
266654 (http://kbalertz.com/Feedback.aspx?kbNumber=266654/) HOWTO: Implement dynamic search functionality to locate records in a DataGrid that is bound to a large ADO Recordset
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