如何比较组合框中的新值和以前的值？

Question

我有datagridview和列，并且类型是combobox.Combobox值是从sql数据库使用。在组合框中“状态”我有5个不同的项目值。我想要的是当我从组合框中更改项目值时按“保存”按钮，我想检查在此之前的值（保存之前）并说：

private void m02BindingNavigatorSaveItem_Click(object sender, EventArgs e)
{
    try
    {
        if (StatusTextBox.Text == "3" && // + want to ask here if previous statusTextBox.text was "1" then to execute lines down if not goes to 'else')
        {
            DialogResult mbox = MessageBox.Show("do you want to save today's  date and time?", "", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
            datumOtvaranjaDateTimePicker.Focus();
            if (mbox == DialogResult.Yes)
            {
                datumOtvaranjaDateTimePicker.Value = DateTime.Now;
            }
            Save();
            Refresh();
        }
        else
        {
            MessageBox.Show("you cant do that!!!" + Environment.NewLine + "Check what you typed and try again", "Upozorenje", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            Refresh();
        }
    }
    catch (Exception)
    {

    }
}

Answer 1

查看this其他答案

  

您可以处理ComboBox.Enter事件。然后保存   SelectedItem或SelectedValue到成员变量

public partial class Form1 : Form 
{
    public Form1()
    {
        InitializeComponent();
        comboBox1.Enter += comboBox1_Enter;
    }

    private void comboBox1_Enter(object sender, EventArgs e)
    {
        m_cb1PrevVal = comboBox1.SelectedValue;
    }

    private void RestoreOldValue()
    {
        comboBox1.SelectedValue = m_cb1PrevVal;
    }
}