如何删除列表框c#中的项目

我试图用数据库值在列表框中添加项目，并尝试使用双击事件将其删除，我想删除列表框中的项目，该项目的价格将扣除到 txtTotal.Text。例如。我在列表框名称“Package1”中添加一个价格为 299 的项目，并添加另一个价格为 300 的项目名称“Package2”，如果我删除“Package1”，txtTotal 将减少 299 的数字，它将变为 300。

这是我的代码：

void fillCombo()
    {

        string constring = "server=localhost;port=3306;username=root;password=root";
        string Query = "Select * from dbinfo.tbladvance;";
        MySqlConnection con = new MySqlConnection(constring);
        MySqlCommand cmdDB = new MySqlCommand(Query, con);
        MySqlDataReader myReader;
        try
        {
            con.Open();
            myReader = cmdDB.ExecuteReader();

            while (myReader.Read())
            {
                string sName = myReader.GetString("Names");
                comboBox1.Items.Add(sName);



            }
            con.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }
    }

    private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string constring = "server=localhost;port=3306;username=root;password=root";
        string Query = "Select * from dbinfo.tbladvance where Names='" + comboBox1.Text + "'  ;";
        MySqlConnection con = new MySqlConnection(constring);
        MySqlCommand cmdDB = new MySqlCommand(Query, con);
        MySqlDataReader myReader;
        try
        {
            con.Open();
            myReader = cmdDB.ExecuteReader();

            while (myReader.Read())
            {
                double sPrice = myReader.GetDouble("Price");
                string sDesc = myReader.GetString("Description");
                txtPrice.Text = sPrice.ToString();
                txtDesc.Text = sDesc;
            }
            con.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }

    }

    int total;
    private void button1_Click(object sender, EventArgs e)
    {
        listBox1.Items.Add(comboBox1.Text);

        int num1 = int.Parse(txtPrice.Text);
        int num2 = int.Parse(txtTotal.Text);

        total = num1 + num2;

        txtTotal.Text = total.ToString();

    }

    private void listBox1_DoubleClick(object sender, EventArgs e)
    {

        string constring = "server=localhost;port=3306;username=root;password=root";
        string Query = "Select * from dbinfo.tbladvance;";
        MySqlConnection con = new MySqlConnection(constring);
        MySqlCommand cmdDB = new MySqlCommand(Query, con);
        MySqlDataReader myReader;

        con.Open();
        myReader = cmdDB.ExecuteReader();

        while (myReader.Read())
        {
            for (int n = listBox1.Items.Count - 1; n >= 0; --n)
            {
                string sName = myReader.GetString("Names");
                string removelistitem = sName;
                if (listBox1.Items[n].ToString().Contains(removelistitem))
                {
                    listBox1.Items.RemoveAt(n);
                }
            }





        }
        con.Close();


    }

顺便说一下，我正在使用 mysql，提前致谢:)