Procedura: esplorare un dataset con il controllo BindingNavigator Windows Form

Durante la compilazione di applicazioni guidate da dati, è spesso necessario visualizzare insiemi di dati per gli utenti. Il controllo BindingNavigator, unitamente al componente BindingSource, rappresenta una soluzione pratica e versatile per spostarsi all'interno di un insieme e visualizzare gli elementi in sequenza.

Esempio

Nell'esempio di codice seguente viene illustrato come utilizzare un controllo BindingNavigator per spostarsi nei dati. L’insieme è contenuto in un oggetto DataView, associato a un controllo TextBox con un componente BindingSource.

Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Data.SqlClient
Imports System.Windows.Forms


' This form demonstrates using a BindingNavigator to display 
' rows from a database query sequentially.
Public Class Form1
    Inherits Form
    ' This is the BindingNavigator that allows the user
    ' to navigate through the rows in a DataSet.
    Private customersBindingNavigator As New BindingNavigator(True)

    ' This is the BindingSource that provides data for
    ' the Textbox control.
    Private customersBindingSource As New BindingSource()

    ' This is the TextBox control that displays the CompanyName
    ' field from the the DataSet.
    Private companyNameTextBox As New TextBox()


    Public Sub New()
        ' Set up the BindingSource component.
        Me.customersBindingNavigator.BindingSource = Me.customersBindingSource
        Me.customersBindingNavigator.Dock = DockStyle.Top
        Me.Controls.Add(Me.customersBindingNavigator)

        ' Set up the TextBox control for displaying company names.
        Me.companyNameTextBox.Dock = DockStyle.Bottom
        Me.Controls.Add(Me.companyNameTextBox)

        ' Set up the form.
        Me.Size = New Size(800, 200)
        AddHandler Me.Load, AddressOf Form1_Load

    End Sub 'New


    Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
        ' Open a connection to the database.
        ' Replace the value of connectString with a valid 
        ' connection string to a Northwind database accessible 
        ' to your system.
        Dim connectString As String = _
            "Integrated Security=SSPI;Persist Security Info=False;" & _
            "Initial Catalog=Northwind;Data Source=localhost"

        Dim connection As New SqlConnection(connectString)
        Try

            Dim dataAdapter1 As New SqlDataAdapter( _
                New SqlCommand("Select * From Customers", connection))
            Dim ds As New DataSet("Northwind Customers")
            ds.Tables.Add("Customers")
            dataAdapter1.Fill(ds.Tables("Customers"))

            ' Assign the DataSet as the DataSource for the BindingSource.
            Me.customersBindingSource.DataSource = ds.Tables("Customers")

            ' Bind the CompanyName field to the TextBox control.
            Me.companyNameTextBox.DataBindings.Add(New Binding("Text", _
                Me.customersBindingSource, "CompanyName", True))
        Finally
            connection.Dispose()
        End Try

    End Sub 'Form1_Load


    <STAThread()> _
    Public Shared Sub Main()
        Application.EnableVisualStyles()
        Application.Run(New Form1())

    End Sub
End Class

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Data.SqlClient;
using System.Windows.Forms;

// This form demonstrates using a BindingNavigator to display 
// rows from a database query sequentially.
public class Form1 : Form
{
    // This is the BindingNavigator that allows the user
    // to navigate through the rows in a DataSet.
    BindingNavigator customersBindingNavigator = new BindingNavigator(true);

    // This is the BindingSource that provides data for
    // the Textbox control.
    BindingSource customersBindingSource = new BindingSource();

    // This is the TextBox control that displays the CompanyName
    // field from the the DataSet.
    TextBox companyNameTextBox = new TextBox();

    public Form1()
    {
        // Set up the BindingSource component.
        this.customersBindingNavigator.BindingSource = this.customersBindingSource;
        this.customersBindingNavigator.Dock = DockStyle.Top;
        this.Controls.Add(this.customersBindingNavigator);

        // Set up the TextBox control for displaying company names.
        this.companyNameTextBox.Dock = DockStyle.Bottom;
        this.Controls.Add(this.companyNameTextBox);

        // Set up the form.
        this.Size = new Size(800, 200);
        this.Load += new EventHandler(Form1_Load);
    }

    void Form1_Load(object sender, EventArgs e)
    {
        // Open a connection to the database.
        // Replace the value of connectString with a valid 
        // connection string to a Northwind database accessible 
        // to your system.
        string connectString =
            "Integrated Security=SSPI;Persist Security Info=False;" +
            "Initial Catalog=Northwind;Data Source=localhost";

        using (SqlConnection connection = new SqlConnection(connectString))
        {

            SqlDataAdapter dataAdapter1 = 
                new SqlDataAdapter(new SqlCommand("Select * From Customers",connection));
            DataSet ds = new DataSet("Northwind Customers");
            ds.Tables.Add("Customers");
            dataAdapter1.Fill(ds.Tables["Customers"]);

            // Assign the DataSet as the DataSource for the BindingSource.
            this.customersBindingSource.DataSource = ds.Tables["Customers"];

            // Bind the CompanyName field to the TextBox control.
            this.companyNameTextBox.DataBindings.Add(
                new Binding("Text",
                this.customersBindingSource,
                "CompanyName",
                true));
        }
    }

    [STAThread]
    public static void Main()
    {
        Application.EnableVisualStyles();
        Application.Run(new Form1());
    }
}

Compilazione del codice

Per questo esempio sono necessari i seguenti requisiti:

• Riferimenti agli assembly System, System.Data, System.Drawing, System.Windows.Forms e System.Xml.

Per informazioni sulla compilazione di questo esempio dalla riga di comando per Visual Basic o Visual C#, vedere Building from the Command Line (Visual Basic) o Compilazione dalla riga di comando con csc.exe. È anche possibile compilare questo esempio in Visual Studio incollando il codice in un nuovo progetto. Per ulteriori informazioni, vedere Procedura: compilare ed eseguire un esempio di codice Windows Form completo tramite Visual Studio e Procedura: compilare ed eseguire un esempio di codice Windows Form completo tramite Visual Studio e Procedura: compilare ed eseguire un esempio di codice Windows Form completo tramite Visual Studio e Procedura: compilare ed eseguire un esempio di codice Windows Form completo tramite Visual Studio e Procedura: compilare ed eseguire un esempio di codice Windows Form completo tramite Visual Studio.

Vedere anche

Attività

Procedura: associare un controllo Windows Form a un tipo

Riferimenti

BindingSource

DataGridView

BindingSource

Altre risorse

Controllo BindingNavigator (Windows Form)

Il componente BindingSource