Convert text column to combobox column in an object bound DataGridView control

using System;
using System.Data;
using System.Text;

namespace SAPS
{
    public class clsPhoneNumber
    {
		#region Fields (4) 

        private int _contacts_FK;
        private string _errMsg;
        private string _phoneNumber;
        private int _phoneNumbers_PK;
        private int _phoneTypes_FK;
        private string _phoneType;

		#endregion Fields 

		#region Constructors (1) 

        public  clsPhoneNumber()
        {
            _errMsg = "";
            _phoneNumbers_PK = 0;
            _phoneTypes_FK = 0;
            _phoneType = "";
            _phoneNumber = "";
            _contacts_FK = 0;
        }

		#endregion Constructors 

		#region Properties (4) 

        public int ContactsFk
        {
            get { return _contacts_FK; }
            set { _contacts_FK = value; }
        }

        public string ErrMsg
        {
            get { return _errMsg; }
            set { _errMsg = value; }
        }

        public string PhoneNumber
        {
            get { return _phoneNumber; }
            set { _phoneNumber = SAPSCommon.Instance.StripNonNumerics(value); }
        }

        public int PhoneNumbersPK
        {
            get { return _phoneNumbers_PK; }
            set { _phoneNumbers_PK = value; }
        }

        public int PhoneTypesFK
        {
            get { return _phoneTypes_FK; }
            set { _phoneTypes_FK = value; }
        }

        public string PhoneType
        {
            get { return _phoneType; }
        }

        #endregion Properties 

		#region Methods (2) 

		// Public Methods (1) 

        /// <summary>
        /// Get the Notes for the specified key
        /// </summary>
        /// <param name="TableID">The Table Primary Key</param>
        /// <returns>An Object containing data for the specified Primary Key</returns>
        public clsPhoneNumber GetData(int TableID)
        {
            AssignProperties(SAPSCommon.Instance.ReadTable("PhoneNumbers", "PN_PhoneNumbers_PK", TableID));
            return this;
        }
		// Private Methods (1) 

        /// <summary>
        /// Assigns the table's data to the properties of the Data Object.
        /// This method must be hand coded for each table.
        /// </summary>
        /// <param name="ds">A Dataset containing the data record read from the Table</param>
        private void AssignProperties(DataSet ds)
        {
            //Assign properties with database data
            try
            {
                //Primary Key for Table
                _phoneNumbers_PK = ds.Tables[0].Rows[0].Field<int>("PN_PhoneNumbers_PK");

                //The rest of the data fields
                _contacts_FK = ds.Tables[0].Rows[0].Field<int>("PN_Contacts_FK");
                _phoneNumber = FormatPhoneNumber(ds.Tables[0].Rows[0].Field<string>("PN_PhoneNum"));
                _phoneTypes_FK = ds.Tables[0].Rows[0].Field<int>("PN_PhoneTypes_FK");

                //Follow links of Foreign Keys
                DataTable dt = new DataTable();
                string sqlSelect =
                    string.Format(
                        "SELECT PT_Description FROM Pensions.dbo.PhoneTypes WHERE PT_PhoneTypes_PK = '{0}'",
                        _phoneTypes_FK);             
                dt = SQLCommon.Instance.SQLSelect(sqlSelect);
                _phoneType = dt.Rows[0].Field<string>("PT_Description");
            }
            catch (Exception e)
            {
                _errMsg = e.Message;
                SAPSCommon.Instance.ShowErrorMsg(e.Message);
            }
        }

        /// <summary>
        /// Format an Australian Phone number
        /// </summary>
        /// <param name="Num">Phone Number to format in string format</param>
        /// <returns>Formatted Phone Number</returns>
        private string FormatPhoneNumber(string Num)
        {
            if (Num.Substring(0, 2) == "04") //Mobile Number
            {
                return string.Format("{0:0### ### ###}", Convert.ToInt64(Num));
            }
            return string.Format("{0:(0#) #### ####}", Convert.ToInt64(Num));
        }

        #endregion Methods 

        public string  Update()
        {
            StringBuilder sb = new StringBuilder("UPDATE [");
            sb.Append(Properties.Settings.Default.SQLDatabaseName);
            sb.Append("].[dbo].[PhoneNumbers] SET PN_Contacts_FK='");
            sb.Append(_contacts_FK);
            sb.Append("', PN_PhoneTypes_FK='");
            sb.Append(_phoneTypes_FK);
            sb.Append("', PN_PhoneNum='");
            sb.Append(_phoneNumber);
            sb.Append("' WHERE PN_PhoneNumbers_PK='");
            sb.Append(_phoneNumbers_PK);
            sb.Append("'");

            _errMsg = SQLCommon.Instance.SQLUpdate(sb.ToString());
            return _errMsg;
        }
    }
}
</string></int></string></int></int>

 private void PopulatePhoneNumbers(clsContacts contacts)
 {
     //Create the 1st column as a textbox for the Phone Number
     DataGridViewTextBoxColumn tb = new DataGridViewTextBoxColumn();
     tb.Name = "PhoneNumber";
     tb.DataPropertyName = "PhoneNumber"; //This is the name of the PhoneNumber object Property for Phone Number

     //Create  2nd column as combobox for PhoneType
     DataGridViewComboBoxColumn cb = new DataGridViewComboBoxColumn();
     cb.Name = "PhoneTypes";
     cb.DataPropertyName = "PhoneTypesFK"; //This is the name of the PhoneNumber object Property for Phone Type

     //Bind the cb to the support table
     string sqlQuery = "SELECT PT_PhoneTypes_PK, PT_Description " +
                       "FROM [Pensions].[dbo].[PhoneTypes] ";
     DataTable dtPhoneTypes = SQLCommon.Instance.SQLSelect(sqlQuery);
     cb.DataSource = dtPhoneTypes;
     cb.ValueMember = dtPhoneTypes.Columns["PT_PhoneTypes_PK"].ColumnName;
     cb.DisplayMember = dtPhoneTypes.Columns["PT_Description"].ColumnName;

     //Add the columns to the grid
     uxContactPhoneNumbersGrd.Columns.Add(tb);
     uxContactPhoneNumbersGrd.Columns.Add(cb);

     //Prevent automatically generating columns for other properties
     uxContactPhoneNumbersGrd.AutoGenerateColumns = false;

     if (contacts.PhoneNumbers != null)
     {
         //Show how many phone numbers
         uxContactPhoneNumbersLbl.Text = string.Format("Phone Numbers ({0})", contacts.PhoneNumbers.Count);
         uxContactPhoneNumbersLbl.Visible = true;

         //Fill Grid
         uxContactPhoneNumbersGrd.DataSource = contacts.PhoneNumbers;

         //Hide non-required columns/rows
         uxContactPhoneNumbersGrd.RowHeadersVisible = false;
     }

     //Adjust text column size and auto wrap
     uxContactPhoneNumbersGrd.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;
     uxContactPhoneNumbersGrd.AutoSizeRowsMode = DataGridViewAutoSizeRowsMode.AllCells;
}