コードの全貌

    public partial class Form2 : Form
    {
        private SqlConnection SqlCon;
        private SqlDataAdapter adapter;
        private SqlCommandBuilder commandBuilder;    public Form2()
    {
        InitializeComponent();
    }
 
    private void Form2_Load(object sender, EventArgs e)
    {
        SqlSettingInitialize();
    }
 
    private void SqlSettingInitialize()
    {
        var sqlConStrBuilder = new SqlConnectionStringBuilder();
        sqlConStrBuilder.InitialCatalog = @"testDb";
        sqlConStrBuilder.DataSource = @"DESKTOP-B9V2BO1";
        sqlConStrBuilder.UserID = "sa";
        sqlConStrBuilder.Password = "pass";
        sqlConStrBuilder.ConnectTimeout = 10;
 
        var selectQuery = @"select * from dbo.test";
 
        SqlCon = new SqlConnection(sqlConStrBuilder.toString());
        adapter = new SqlDataAdapter(selectQuery, SqlCon);
        commandBuilder = new SqlCommandBuilder(adapter);
        adapter.UpdateCommand = commandBuilder.GetUpdateCommand();
    }
 
    private void button1_Click(object sender, EventArgs e)
    {
        var dt = new DataTable();
        SqlCon.Open();
        adapter.Fill(dt);
        SqlCon.Close();
        dataGridView1.DataSource = dt;
    }
 
    private void button2_Click(object sender, EventArgs e)
    {
        var updateDt = (DataTable) dataGridView1.DataSource;
        SqlCon.Open();
        adapter.Update(updateDt);
        SqlCon.Close();
    }
}