Condividi tramite

Procedura: esplorare un dataset con il controllo BindingNavigator di Windows Form

  • Articolo

Durante la creazione di applicazioni basate sui dati, è spesso necessario visualizzare raccolte di dati agli utenti. Il controllo BindingNavigator, unitamente al componente BindingSource, rappresenta una soluzione pratica e versatile per spostarsi all'interno di una raccolta e visualizzare gli elementi in sequenza.

Esempio

L'esempio di codice seguente illustra come usare un controllo BindingNavigator per spostarsi all'interno dei dati. Il set è contenuto in una classe DataView, associata a un controllo TextBox con un componente BindingSource.

Nota

L'archiviazione delle informazioni riservate, ad esempio la password, nella stringa di connessione può avere implicazioni sulla sicurezza dell'applicazione. L'autenticazione di Windows, detta anche sicurezza integrata, consente di controllare l'accesso a un database in modo più sicuro. Per altre informazioni, vedere Protezione delle informazioni di connessione.

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 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());
    }
}

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 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


    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


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

    End Sub
End Class

Compilazione del codice

L'esempio presenta i requisiti seguenti:

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

Vedi anche