如何刷新按钮上的下拉菜单单击其他表格

Question

I have a winform say winForm1 which has combobox. i am binding this combobox on Form_Load event like this

SqlCommand cmd = new SqlCommand("SELECT DISTINCT(TXT_TARGET_NUMBER) FROM TBL_CDR_ANALYZER", sqlCon);
cboTargetNo.Properties.Items.Clear();
cboTargetNo.Properties.Items.Add("Choose Target Number");
sqlCon.Open();
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
    cboTargetNo.Properties.Items.Add(dr["TXT_TARGET_NUMBER"]);
}
sqlCon.Close();
cboTargetNo.SelectedIndex = 0;

Now this form also contains a button say btn1. on Click event of this button i am opening a new winform say winForm2 using ShowDialog() function.

On WinForm2 i have a button btn2 which insert some values in sql. i want after values insert in sql, Combobox on winForm1 should Refresh. How can i do this. i am clueless where to start for this.

Answer 1

If you want to update each form1 from form2 better option is having event handler.

Form2 Code

public event EventHandler myEvent;
public Form2()
{
    InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
    // update data here 

    // inform form 2 about data added 
    if (myEvent != null)
    {
        myEvent(this,e);
    }
}

Form1 Code

public Form1()
{
    InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
    Form2 f2 = new Form2();
    f2.myEvent += new EventHandler(f2_myEvent);
    f2.ShowDialog();
}

void f2_myEvent(object sender, EventArgs e)
{
    //Refresh your ddl
}

Answer 2

Simplist way would be to to extract the code for ComboBox update to a method, Call it from Form_Load event , Later since you are using Form.ShowDialog , you can call the method again to get the latest record from the database and bind the CombobBox again. Something like:

WinForm2 frm2 = new WinForm2();
frm2.ShowDialog();
RefreshCombo();

Where RefreshCombo is a method :

private void RefreshCombo()
{
 SqlCommand cmd = new SqlCommand("SELECT DISTINCT(TXT_TARGET_NUMBER) FROM TBL_CDR_ANALYZER", sqlCon);
cboTargetNo.Properties.Items.Clear();
cboTargetNo.Properties.Items.Add("Choose Target Number");
sqlCon.Open();
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
    cboTargetNo.Properties.Items.Add(dr["TXT_TARGET_NUMBER"]);
}
sqlCon.Close();
cboTargetNo.SelectedIndex = 0;
}

Answer 3

If you want immediate update, you could create a delegate to refresh the Combo from your dialog after hitting the button.

Create a delegate in your main form:

public delegate void ComboDelegate();//namespace level

public void RefreshCombo(string itemToAdd){
   //do your add item here
}

then in your Dialog Form class:

public ComboDelegate cd;

Create your Dialog Form with the cd set to RefreshCombo:

winForm2 = new Winform(){ cd = RefreshCombo );

then at your button Click simply call:

cd(itemToUpdate);