private void button1_Click(object sender, EventArgs e)
        {
            string server = this.textBox1.Text.Trim();
            string name   = this.textBox2.Text.Trim();
            string pwd    = this.textBox3.Text.Trim();

            connectionStr = string.Format("server={0};port=3306;user={1};password={2};", server, name, pwd);
            List <string> dataBaseList = ser.queryAllDataBase(connectionStr);

            if (dataBaseList != null)
            {
                this.comboBox1.Items.Clear();
                foreach (string s in dataBaseList)
                {
                    this.comboBox1.Items.Add(s);
                }
                this.comboBox1.Enabled       = true;
                this.comboBox1.SelectedIndex = 0;
                this.button1.Enabled         = false;
                this.button2.Enabled         = true;
                this.textBox6.Text           = "连接成功!";
            }
        }