Get name of actual used GUI Element (comboBox) to use in Method C# WinForms

Question

I have a Method that removes special Items from comboBoxes. At first the comboboxes are filled with table names from a database and then I want to remove some of them that are not needed in the list. I do this by filling and removing the Items of all comboboxes at the same time. But now I want only the comboBox that I actually use beeing filled and items removed on Dropdown. So I think I need to get the name of the actual used comboBox to use it as a variable or somethink like that. How do I do this?

Here is my code until now. You see its very long for just adding and remove Items of a comboBox.

        //Load DB Tables when Drop Down the Dropboxes. And remove not used/needed tables from Combobox.
    private void referenzDropDown(object sender, EventArgs e)
    {
        string myInsertQuery = "SHOW TABLES";
        MySqlCommand myCommand = new MySqlCommand(myInsertQuery, myConnection);
        MySqlDataReader myReader;
        myReader = myCommand.ExecuteReader();
        comboBox18.Items.Clear();
        comboBox19.Items.Clear();
        comboBox20.Items.Clear();
        comboBox21.Items.Clear();
        comboBox22.Items.Clear();
        comboBox23.Items.Clear();
        comboBox24.Items.Clear();
        comboBox25.Items.Clear();
        comboBox26.Items.Clear();
        if (myReader.HasRows == true)
        {
            while (myReader.Read())
            {
                comboBox18.Items.Add((string)myReader[0]);
                comboBox19.Items.Add((string)myReader[0]);
                comboBox20.Items.Add((string)myReader[0]);
                comboBox21.Items.Add((string)myReader[0]);
                comboBox22.Items.Add((string)myReader[0]);
                comboBox23.Items.Add((string)myReader[0]);
                comboBox24.Items.Add((string)myReader[0]);
                comboBox25.Items.Add((string)myReader[0]);
                comboBox26.Items.Add((string)myReader[0]);
            }
            myReader.Close();
        }
        comboBox18.Items.Remove("referenzen");
        comboBox18.Items.Remove("waage1");
        comboBox18.Items.Remove("waage2");
        comboBox18.Items.Remove("waage3");
        comboBox18.Items.Remove("waage4");
        comboBox18.Items.Remove("waage5");
        comboBox18.Items.Remove("waage6");
        comboBox18.Items.Remove("waage7");
        comboBox18.Items.Remove("waage8");

        comboBox19.Items.Remove("referenzen");
        comboBox19.Items.Remove("waage1");
        comboBox19.Items.Remove("waage2");
        comboBox19.Items.Remove("waage3");
        comboBox19.Items.Remove("waage4");
        comboBox19.Items.Remove("waage5");
        comboBox19.Items.Remove("waage6");
        comboBox19.Items.Remove("waage7");
        comboBox19.Items.Remove("waage8");

        comboBox20.Items.Remove("referenzen");
        comboBox20.Items.Remove("waage1");
        comboBox20.Items.Remove("waage2");
        comboBox20.Items.Remove("waage3");
        comboBox20.Items.Remove("waage4");
        comboBox20.Items.Remove("waage5");
        comboBox20.Items.Remove("waage6");
        comboBox20.Items.Remove("waage7");
        comboBox20.Items.Remove("waage8");

        comboBox21.Items.Remove("referenzen");
        comboBox21.Items.Remove("waage1");
        comboBox21.Items.Remove("waage2");
        comboBox21.Items.Remove("waage3");
        comboBox21.Items.Remove("waage4");
        comboBox21.Items.Remove("waage5");
        comboBox21.Items.Remove("waage6");
        comboBox21.Items.Remove("waage7");
        comboBox21.Items.Remove("waage8");

        comboBox22.Items.Remove("referenzen");
        comboBox22.Items.Remove("waage1");
        comboBox22.Items.Remove("waage2");
        comboBox22.Items.Remove("waage3");
        comboBox22.Items.Remove("waage4");
        comboBox22.Items.Remove("waage5");
        comboBox22.Items.Remove("waage6");
        comboBox22.Items.Remove("waage7");
        comboBox22.Items.Remove("waage8");

        comboBox23.Items.Remove("referenzen");
        comboBox23.Items.Remove("waage1");
        comboBox23.Items.Remove("waage2");
        comboBox23.Items.Remove("waage3");
        comboBox23.Items.Remove("waage4");
        comboBox23.Items.Remove("waage5");
        comboBox23.Items.Remove("waage6");
        comboBox23.Items.Remove("waage7");
        comboBox23.Items.Remove("waage8");

        comboBox24.Items.Remove("referenzen");
        comboBox24.Items.Remove("waage1");
        comboBox24.Items.Remove("waage2");
        comboBox24.Items.Remove("waage3");
        comboBox24.Items.Remove("waage4");
        comboBox24.Items.Remove("waage5");
        comboBox24.Items.Remove("waage6");
        comboBox24.Items.Remove("waage7");
        comboBox24.Items.Remove("waage8");

        comboBox25.Items.Remove("referenzen");
        comboBox25.Items.Remove("waage1");
        comboBox25.Items.Remove("waage2");
        comboBox25.Items.Remove("waage3");
        comboBox25.Items.Remove("waage4");
        comboBox25.Items.Remove("waage5");
        comboBox25.Items.Remove("waage6");
        comboBox25.Items.Remove("waage7");
        comboBox25.Items.Remove("waage8");

        comboBox26.Items.Remove("referenzen");
        comboBox26.Items.Remove("waage1");
        comboBox26.Items.Remove("waage2");
        comboBox26.Items.Remove("waage3");
        comboBox26.Items.Remove("waage4");
        comboBox26.Items.Remove("waage5");
        comboBox26.Items.Remove("waage6");
        comboBox26.Items.Remove("waage7");
        comboBox26.Items.Remove("waage8");


    }

I think it should be something like (pseudocode):

        //Load DB Tables when Drop Down the Dropboxes. And remove not used/needed tables from Combobox.
    private void referenzDropDown(object sender, EventArgs e)
    {
        string myInsertQuery = "SHOW TABLES";
        MySqlCommand myCommand = new MySqlCommand(myInsertQuery, myConnection);
        MySqlDataReader myReader;
        myReader = myCommand.ExecuteReader();

        ActualSelectedComboBox.Items.Clear();

        if (myReader.HasRows == true)
        {
            while (myReader.Read())
            {
                ActualSelectedComboBox.Items.Add((string)myReader[0]);
            }
            myReader.Close();
        }
        ActualSelectedComboBox.Items.Remove("referenzen");
        ActualSelectedComboBox.Items.Remove("waage1");
        ActualSelectedComboBox.Items.Remove("waage2");
        ActualSelectedComboBox.Items.Remove("waage3");
        ActualSelectedComboBox.Items.Remove("waage4");
        ActualSelectedComboBox.Items.Remove("waage5");
        ActualSelectedComboBox.Items.Remove("waage6");
        ActualSelectedComboBox.Items.Remove("waage7");
        ActualSelectedComboBox.Items.Remove("waage8");
    }

Could someone tell me how to do this best way? Thank you!

Answer 1

The sender argument to your event handler is the used combobox. You can simply parse it to ComboBox:

private void referenzDropDown(object sender, EventArgs e)
{
    string myInsertQuery = "SHOW TABLES";
    MySqlCommand myCommand = new MySqlCommand(myInsertQuery, myConnection);
    MySqlDataReader myReader;
    myReader = myCommand.ExecuteReader();

    // the "sender" is the control raising this event
    // parse it to ComboBox
    ComboBox actualSelectedComboBox = (ComboBox)sender;

    actualSelectedComboBox.Items.Clear();
    // ...