Procedura: associare dati al controllo DataGridView di Windows Form

Articolo
09/12/2008

Aggiornamento: novembre 2007

Il controllo DataGridView supporta il modello di associazione dati standard di Windows Form ed è quindi possibile associarlo a varie origini dati. Nella maggior parte dei casi, tuttavia, l'associazione viene eseguita a un componente BindingSource, che gestisce i dettagli dell'interazione con l'origine dati. Il componente BindingSource può rappresentare qualsiasi origine dati di Windows Form e offre una notevole flessibilità per la scelta o la modifica del percorso dei dati. Per ulteriori informazioni sulle origini dati supportate dal controllo DataGridView, vedere Cenni preliminari sul controllo DataGridView (Windows Form).

È disponibile un supporto completo per questa attività in Visual Studio.

Procedura

Per collegare un controllo DataGridView ai dati

Implementare un metodo per gestire il recupero dei dati da un database. Nell'esempio di codice riportato di seguito è implementato un metodo GetData che inizializza un componente SqlDataAdapter e lo utilizza per popolare la classe DataTable. La classe DataTable viene quindi associata al componente BindingSource. Accertarsi di impostare la variabile connectionString su un valore appropriato per il database in uso. Sarà necessario accedere a un server in cui sia installato il database SQL Server di esempio Northwind.

Private Sub GetData(ByVal selectCommand As String)

    Try
        ' Specify a connection string. Replace the given value with a 
        ' valid connection string for a Northwind SQL Server sample
        ' database accessible to your system.
        Dim connectionString As String = _
            "Integrated Security=SSPI;Persist Security Info=False;" + _
            "Initial Catalog=Northwind;Data Source=localhost"

        ' Create a new data adapter based on the specified query.
        Me.dataAdapter = New SqlDataAdapter(selectCommand, connectionString)

        ' Create a command builder to generate SQL update, insert, and
        ' delete commands based on selectCommand. These are used to
        ' update the database.
        Dim commandBuilder As New SqlCommandBuilder(Me.dataAdapter)

        ' Populate a new data table and bind it to the BindingSource.
        Dim table As New DataTable()
        table.Locale = System.Globalization.CultureInfo.InvariantCulture
        Me.dataAdapter.Fill(table)
        Me.bindingSource1.DataSource = table

        ' Resize the DataGridView columns to fit the newly loaded content.
        Me.dataGridView1.AutoResizeColumns( _
            DataGridViewAutoSizeColumnsMode.AllCellsExceptHeader)
    Catch ex As SqlException
        MessageBox.Show("To run this example, replace the value of the " + _
            "connectionString variable with a connection string that is " + _
            "valid for your system.")
    End Try

End Sub

private void GetData(string selectCommand)
{
    try
    {
        // Specify a connection string. Replace the given value with a 
        // valid connection string for a Northwind SQL Server sample
        // database accessible to your system.
        String connectionString =
            "Integrated Security=SSPI;Persist Security Info=False;" +
            "Initial Catalog=Northwind;Data Source=localhost";

        // Create a new data adapter based on the specified query.
        dataAdapter = new SqlDataAdapter(selectCommand, connectionString);

        // Create a command builder to generate SQL update, insert, and
        // delete commands based on selectCommand. These are used to
        // update the database.
        SqlCommandBuilder commandBuilder = new SqlCommandBuilder(dataAdapter);

        // Populate a new data table and bind it to the BindingSource.
        DataTable table = new DataTable();
        table.Locale = System.Globalization.CultureInfo.InvariantCulture;
        dataAdapter.Fill(table);
        bindingSource1.DataSource = table;

        // Resize the DataGridView columns to fit the newly loaded content.
        dataGridView1.AutoResizeColumns( 
            DataGridViewAutoSizeColumnsMode.AllCellsExceptHeader);
    }
    catch (SqlException)
    {
        MessageBox.Show("To run this example, replace the value of the " +
            "connectionString variable with a connection string that is " +
            "valid for your system.");
    }
}

Nel gestore eventi Load del form associare il controllo DataGridView al componente BindingSource e chiamare il metodo GetData per recuperare i dati dal database.

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) _
    Handles Me.Load

    ' Bind the DataGridView to the BindingSource
    ' and load the data from the database.
    Me.dataGridView1.DataSource = Me.bindingSource1
    GetData("select * from Customers")

End Sub

private void Form1_Load(object sender, System.EventArgs e)
{
    // Bind the DataGridView to the BindingSource
    // and load the data from the database.
    dataGridView1.DataSource = bindingSource1;
    GetData("select * from Customers");
}

Esempio

Nell'esempio di codice completo riportato di seguito vengono forniti i pulsanti che consentono di ricaricare i dati dal database e di inoltrare modifiche al database.

Imports System
Imports System.Data
Imports System.Data.SqlClient
Imports System.Windows.Forms

Public Class Form1
    Inherits System.Windows.Forms.Form

    Private dataGridView1 As New DataGridView()
    Private bindingSource1 As New BindingSource()
    Private dataAdapter As New SqlDataAdapter()
    Private WithEvents reloadButton As New Button()
    Private WithEvents submitButton As New Button()

    <STAThreadAttribute()> _
    Public Shared Sub Main()
        Application.Run(New Form1())
    End Sub

    ' Initialize the form.
    Public Sub New()

        Me.dataGridView1.Dock = DockStyle.Fill

        Me.reloadButton.Text = "reload"
        Me.submitButton.Text = "submit"

        Dim panel As New FlowLayoutPanel()
        panel.Dock = DockStyle.Top
        panel.AutoSize = True
        panel.Controls.AddRange(New Control() {Me.reloadButton, Me.submitButton})

        Me.Controls.AddRange(New Control() {Me.dataGridView1, panel})
        Me.Text = "DataGridView databinding and updating demo"

    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) _
        Handles Me.Load

        ' Bind the DataGridView to the BindingSource
        ' and load the data from the database.
        Me.dataGridView1.DataSource = Me.bindingSource1
        GetData("select * from Customers")

    End Sub

    Private Sub reloadButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) _
        Handles reloadButton.Click

        ' Reload the data from the database.
        GetData(Me.dataAdapter.SelectCommand.CommandText)

    End Sub

    Private Sub submitButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) _
        Handles submitButton.Click

        ' Update the database with the user's changes.
        Me.dataAdapter.Update(CType(Me.bindingSource1.DataSource, DataTable))

    End Sub

    Private Sub GetData(ByVal selectCommand As String)

        Try
            ' Specify a connection string. Replace the given value with a 
            ' valid connection string for a Northwind SQL Server sample
            ' database accessible to your system.
            Dim connectionString As String = _
                "Integrated Security=SSPI;Persist Security Info=False;" + _
                "Initial Catalog=Northwind;Data Source=localhost"

            ' Create a new data adapter based on the specified query.
            Me.dataAdapter = New SqlDataAdapter(selectCommand, connectionString)

            ' Create a command builder to generate SQL update, insert, and
            ' delete commands based on selectCommand. These are used to
            ' update the database.
            Dim commandBuilder As New SqlCommandBuilder(Me.dataAdapter)

            ' Populate a new data table and bind it to the BindingSource.
            Dim table As New DataTable()
            table.Locale = System.Globalization.CultureInfo.InvariantCulture
            Me.dataAdapter.Fill(table)
            Me.bindingSource1.DataSource = table

            ' Resize the DataGridView columns to fit the newly loaded content.
            Me.dataGridView1.AutoResizeColumns( _
                DataGridViewAutoSizeColumnsMode.AllCellsExceptHeader)
        Catch ex As SqlException
            MessageBox.Show("To run this example, replace the value of the " + _
                "connectionString variable with a connection string that is " + _
                "valid for your system.")
        End Try

    End Sub

End Class

using System;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;

public class Form1 : System.Windows.Forms.Form
{
    private DataGridView dataGridView1 = new DataGridView();
    private BindingSource bindingSource1 = new BindingSource();
    private SqlDataAdapter dataAdapter = new SqlDataAdapter();
    private Button reloadButton = new Button();
    private Button submitButton = new Button();

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

    // Initialize the form.
    public Form1()
    {
        dataGridView1.Dock = DockStyle.Fill;

        reloadButton.Text = "reload";
        submitButton.Text = "submit";
        reloadButton.Click += new System.EventHandler(reloadButton_Click);
        submitButton.Click += new System.EventHandler(submitButton_Click);

        FlowLayoutPanel panel = new FlowLayoutPanel();
        panel.Dock = DockStyle.Top;
        panel.AutoSize = true;
        panel.Controls.AddRange(new Control[] { reloadButton, submitButton });

        this.Controls.AddRange(new Control[] { dataGridView1, panel });
        this.Load += new System.EventHandler(Form1_Load);
        this.Text = "DataGridView databinding and updating demo";
    }

    private void Form1_Load(object sender, System.EventArgs e)
    {
        // Bind the DataGridView to the BindingSource
        // and load the data from the database.
        dataGridView1.DataSource = bindingSource1;
        GetData("select * from Customers");
    }

    private void reloadButton_Click(object sender, System.EventArgs e)
    {
        // Reload the data from the database.
        GetData(dataAdapter.SelectCommand.CommandText);
    }

    private void submitButton_Click(object sender, System.EventArgs e)
    {
        // Update the database with the user's changes.
        dataAdapter.Update((DataTable)bindingSource1.DataSource);
    }

    private void GetData(string selectCommand)
    {
        try
        {
            // Specify a connection string. Replace the given value with a 
            // valid connection string for a Northwind SQL Server sample
            // database accessible to your system.
            String connectionString =
                "Integrated Security=SSPI;Persist Security Info=False;" +
                "Initial Catalog=Northwind;Data Source=localhost";

            // Create a new data adapter based on the specified query.
            dataAdapter = new SqlDataAdapter(selectCommand, connectionString);

            // Create a command builder to generate SQL update, insert, and
            // delete commands based on selectCommand. These are used to
            // update the database.
            SqlCommandBuilder commandBuilder = new SqlCommandBuilder(dataAdapter);

            // Populate a new data table and bind it to the BindingSource.
            DataTable table = new DataTable();
            table.Locale = System.Globalization.CultureInfo.InvariantCulture;
            dataAdapter.Fill(table);
            bindingSource1.DataSource = table;

            // Resize the DataGridView columns to fit the newly loaded content.
            dataGridView1.AutoResizeColumns( 
                DataGridViewAutoSizeColumnsMode.AllCellsExceptHeader);
        }
        catch (SqlException)
        {
            MessageBox.Show("To run this example, replace the value of the " +
                "connectionString variable with a connection string that is " +
                "valid for your system.");
        }
    }

}

Compilazione del codice

L'esempio presenta i seguenti requisiti:

Riferimenti agli assembly System, System.Windows.Forms, System.Data e System.XML.

Per informazioni sulla generazione di questo esempio dalla riga di comando per Visual Basic o Visual C#, vedere Compilazione dalla riga di comando (Visual Basic) o Compilazione dalla riga di comando con csc.exe. È anche possibile generare questo esempio in Visual Studio incollando il codice in un nuovo progetto.

Sicurezza

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

Vedere anche

Procedura: associare dati al controllo DataGridView di Windows Form

Procedura

Per collegare un controllo DataGridView ai dati

Esempio

Compilazione del codice

Sicurezza

Vedere anche

Concetti

Riferimenti

Altre risorse

Risorse aggiuntive