通过列表视图和文本框更新数据

我做了一个数据库应用程序。目前我有一个添加和删除功能，但现在我正在寻找更新功能的帮助。我在这个网站上搜索了所有的答案，但我猜没有运气。所以我想要的是，如果我点击ListView中的记录，它会自动显示在文本框中，这样我就可以改变的东西，当我点击按钮"更新"它必须更新的记录。

帮助将非常感激!

my code of Form1

        public SqlCeConnection conn = new SqlCeConnection(@"Data Source=E:'Users'Ali'Documents'automail.sdf");


    ////////////////////////////////////Methodes////////////////////////////////////
    private void Populate()
    {
        SqlCeCommand cm = new SqlCeCommand("SELECT * FROM Emails ORDER BY principalID", conn);
        listView1.Items.Clear();
        try
        {
            SqlCeDataReader dr = cm.ExecuteReader();
            while (dr.Read())
            {
                ListViewItem it = new ListViewItem(dr["principalID"].ToString());
                it.SubItems.Add(dr["email"].ToString());
                it.SubItems.Add(dr["query"].ToString());
                it.SubItems.Add(dr["subject"].ToString());
                listView1.Items.Add(it);        
            }
            dr.Close();
            dr.Dispose();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
            Application.ExitThread();
        }
    }



    ////////////////////////////////////Methodes////////////////////////////////////
    // Insert button (for data insert)
    private void button1_Click(object sender, EventArgs e)
    {
        if (textBox1.Text == "" || textBox2.Text == "" || textBox3.Text == "")
        {
            MessageBox.Show("Fill in all the information first!");
        }
        else
        {
            SqlCeCommand cmd = new SqlCeCommand("INSERT INTO Emails(principalID, email, query, subject) VALUES(@principalID, @email, @query, @subject)", conn);
            cmd.Connection = conn;
            cmd.Parameters.AddWithValue("@principalID", textBox1.Text);
            cmd.Parameters.AddWithValue("@query", textBox2.Text);
            cmd.Parameters.AddWithValue("@email", textBox3.Text);
            cmd.Parameters.AddWithValue("@subject", textBox4.Text);
            try
            {
                int affectedrows = cmd.ExecuteNonQuery();
                if (affectedrows > 0)
                {
                    Populate();
                    MessageBox.Show("Email added successfully!");    
                }
                else
                {
                    MessageBox.Show("Failed to add email!");
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        } 
    }
    //if form shown update listview
    private void Form1_Shown(object sender, EventArgs e)
    {
        try
        {
            conn.Open();
            Populate();
        }
        catch (SqlCeException ex)
        {
            MessageBox.Show(ex.Message);
            Application.ExitThread();
        }
    }
    //open form 2 and hide this
    private void button2_Click(object sender, EventArgs e)
    {
        this.Hide();
        Form2 form2 = new Form2();
        form2.Show();
    }
    private void Form1_Load(object sender, EventArgs e)
    {
    }
    //if listview selected enable button, else disable
    private void listView1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (listView1.SelectedItems.Count > 0)
        {
            button3.Enabled = true;
        }
        else
        {
            button3.Enabled = false;
        }
    }
    private void button3_Click(object sender, EventArgs e)
    {
    }
    //delete record button
    private void button3_Click_1(object sender, EventArgs e)
    {
        if (listView1.SelectedItems.Count <= 0)
        {
            MessageBox.Show("Select a record!");
        }
        else
        {
            for (int i = 0; i < listView1.SelectedItems.Count; i++)
            {
                SqlCeCommand cm = new SqlCeCommand("DELETE FROM Emails WHERE principalID = @principalID", conn);
                cm.Parameters.AddWithValue("@principalID", listView1.SelectedItems[0].Text);
                try
                {
                    cm.ExecuteNonQuery();
                    Populate();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
            }   
        }
    }
    private void button2_Click_1(object sender, EventArgs e)
    {
        if (listView1.SelectedItems.Count > 0)
        {
            ListViewItem itm = listView1.SelectedItems[0];
            string principalid = itm.SubItems[0].Text;
            string query = itm.SubItems[1].Text;
            string email = itm.SubItems[2].Text;
            Form2 form2 = new Form2();
            form2.Show();
            form2.PrincipalID = principalid;
            form2.Query = query;
            form2.Email = email;
        }
    }
    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
    }
}

}