How Do I Remove This Erroe

Namespace HOSPITAL_MANAGEMENT_SYSTEM.Forms
{
    public partial class Doctor_Page : DevExpress.XtraEditors.XtraForm
    {
        public Doctor_Page()
        {
            InitializeComponent();
        }
        HOSPITAL_MANAGEMENT_SYSTEM.dataaccess dbcs = new dataaccess();

        private void Doctor_Page_Load(object sender, EventArgs e)
        {

        }

        private void btn_save_Click(object sender, EventArgs e)
        {
            DateTime datee = DateTime.Parse(date.EditValue.ToString());
            //DateTime dateee = 
            string starttime = txtbx_starttime.Text.Trim();
            string endtime = txtbx_endtime.Text.Trim();
            string patienttype = combo_patnttype.SelectedIndex.ToString();
            string patientfee = txtbx_patntfee.Text.Trim();
            string patientname = txtbx_patntname.Text.Trim();
            string phonnum = txtbx_phnnum.Text.Trim();
            string appoint = combo_appointtype.SelectedIndex.ToString();
            string insert = string.Format("insert into doctor values({0},'{1}','{2}','{3}',{4},'{5}',{6},'{7}')", datee, starttime, endtime,patienttype,patientfee,patientname, phonnum, appoint);
            SqlCommand sqlcm = new SqlCommand (insert, dbcs.open());
            sqlcm.ExecuteNonQuery();
            

        }