using System;
using System.Data;
using System.Windows.Forms;

namespace WinFormApp1
{
    public partial class Form1 : Form
    {
        DataGridView dataGridView;
        public Form1()
        {
            //InitializeComponent();
            Width = 500;

            var timeTable = new DataTable("timeTable");
            timeTable.Columns.Add("ID_Timetable", typeof(int));
            timeTable.Columns.Add("Date", typeof(DateTime));
            timeTable.Columns.Add("ID_Service", typeof(int));

            timeTable.Rows.Add(6, new DateTime(2019, 05, 18));
            timeTable.Rows.Add(7, new DateTime(2019, 05, 17));
            timeTable.Rows.Add(8, new DateTime(2019, 05, 16));


            var services = new DataTable("services");
            services.Columns.Add("ID_Service", typeof(int));
            services.Columns.Add("Name_service", typeof(string));

            services.Rows.Add(1, "Foo");
            services.Rows.Add(2, "Bar");
            services.Rows.Add(3, "Baz");


            var bindingSourceTimeTable = new BindingSource();
            bindingSourceTimeTable.DataSource = timeTable;

            var bindingSourceServices = new BindingSource();
            bindingSourceServices.DataSource = services;


            var serviceNameColumn = new DataGridViewComboBoxColumn();
            serviceNameColumn.DataSource = bindingSourceServices;

            serviceNameColumn.DataPropertyName = "ID_Service"; // внешний ключ
            serviceNameColumn.DisplayMember = "Name_service";
            serviceNameColumn.ValueMember = "ID_Service"; // первичный ключ


            dataGridView = new DataGridView { Parent = this, Dock = DockStyle.Top };
            dataGridView.DataSource = bindingSourceTimeTable;
            dataGridView.Columns.Add(serviceNameColumn);
        }
    }
}