ComboBox不更新

Question

I got a comboBox in FORM1 that gets the value from the database

FORM1 Code:

public void fillComboBox()
{           
    using (SqlConnection myDatabaseConnection = new SqlConnection(myConnectionString.ConnectionString))
    {
         myDatabaseConnection.Open();
         using (SqlCommand mySqlCommand = new SqlCommand("Select LastName, FirstName, MiddleName from EMP", myDatabaseConnection))
         using (SqlDataReader sqlreader = mySqlCommand.ExecuteReader())
         {
             while (sqlreader.Read())
             {
                 string Lname = sqlreader.GetString(sqlreader.GetOrdinal("LastName"));
                 string Fname = sqlreader.GetString(sqlreader.GetOrdinal("FirstName"));
                 string Mname = sqlreader.GetString(sqlreader.GetOrdinal("MiddleName"));
                 string fullName = Lname + ", " + Fname + " " + Mname; 
                 comboBox3.Items.Add(fullName);
             }
         }
    }
}

From the FORM1 I have a button that opens the FORM2 where I could add data in the database.

FORM2 Code:

public void addData()
{
    string a = "INSERT INTO Emp(LastName, FirstName, MiddleName) Values('"+textBox1.Text+"', '"+textBox2.Text+"', '"+textBox3.Text+"')";

    using (SqlConnection myDatabaseConnection1 = new SqlConnection(myConnectionString.ConnectionString))
    {
         myDatabaseConnection1.Open();
         using (SqlCommand mySqlCommand = new SqlCommand(" " + a + " ", myDatabaseConnection1))
         mySqlCommand.ExecuteReader();
    }  
}

private void button1_Click(object sender, EventArgs e)
{
    addData();
    Form1 nf = new Form1();
    nf.fillComboBox();
    this.close
}

I check the database and verified the data is added.
The problem is when I add data in the datatabase the comboBox don't update the data it loads. It only updates after I run the program again.

Answer 1

With this code:

Form1 nf = new Form1();
nf.fillComboBox();

You are creating a new Form1 after db update (and not showing it). You are not refreshing the original Form1 .

To see this, add: nf.Show(); after the fillComboBox() call.

You have to refresh the original Form1 after closing Form2 .

example:

if(form2.ShowDialog() == DialogResult.OK)
    fillComboBox();

and in fillComboBox , you should clear comboBox3.Items before adding new entries.