Public Class Person
    Public Property GuidPerson As Guid
    Public Property FirstName As String
    Public Property LastName As String
    Public ReadOnly Property FullName As String
        Get
            Return String.Format("{0} {1}", FirstName, LastName)
        End Get
    End Property
    Public Sub New(fName As String, lname As String)
        GuidPerson = Guid.NewGuid
        FirstName = fName
        LastName = lname
    End Sub
End Class

Public Class RadForm4
    Private listPerson As New List(Of Person)
    Public Sub New()
        InitializeComponent()

        listPerson.Add(New Person("John", "Snow"))
        listPerson.Add(New Person("Arya", "Stark"))
        listPerson.Add(New Person("Brandon", "Stark"))
        listPerson.Add(New Person("Catelyn", "Stark"))

        RadTextBoxControl1.AutoCompleteMode = AutoCompleteMode.Suggest
        RadTextBoxControl1.AutoCompleteDataSource = listPerson
        RadTextBoxControl1.AutoCompleteDisplayMember = "FullName"

    End Sub
    Private Sub RadButton1_Click(sender As Object, e As EventArgs) Handles RadButton1.Click
        'HOW TAKE 'GuidPerson' from selected item in RadTextBoxControl1
    End Sub
End Class

Dim searchValue As Person = TryCast(RadDropDownList1.SelectedItem.DataBoundItem, Person)

    public partial class Shifts
    {
        public int empId { get; set; }
        public int Id { get; set; }
        public int day { get; set; }
        public System.DateTime start { get; set; }
        public System.DateTime end { get; set; }
        public int location { get; set; }
    
        public virtual employee employee { get; set; }
    }

    public partial class location
    {
        public location()
        {
            this.Shifts = new HashSet<Shifts>();
        }
    
        public int Id { get; set; }
        public string name { get; set; }
   
        public virtual ICollection<Shifts> Shifts { get; set; }

    }

public partial class employee
    {
        public employee()
        {
            this.aktiveSchichten = new HashSet<Shifts>();
        }
    
        public int Id { get; set; }
        public string firstName { get; set; }
        public string lastName { get; set; }

        public virtual ICollection<aktiveSchichten> aktiveSchichten { get; set; }
    }

 var mitarbeiter = db.employee;
            var schichten = db.Shifts.Where(a => a.location == (int)radMultiColumnComboBox2.SelectedValue);
            foreach (var schicht in schichten)
            {
                radScheduler1.Appointments.BeginUpdate();
                int count = 1;
                foreach (var ma in mitarbeiter)
                {
                    this.radScheduler1.Resources.Add(new Resource(count++, ma.firstName + ma.lastName));
                }
                DateTime start = ?;
                DateTime end = ?;
                Appointment appointment1 = new Appointment(start, end, schicht.employee.firstName + schicht.employee.firstName, "test");
                appointment1.BackgroundId = (int)AppointmentBackground.Anniversary;
                appointment1.StatusId = (int)AppointmentStatus.Unavailable;
                radScheduler1.Appointments.Add(appointment1);
                radScheduler1.Appointments.EndUpdate();
           }

 private void RadGridView1_RowFormatting(object sender, RowFormattingEventArgs e)
        {
            try
            {
                if ((string)e.RowElement.RowInfo.Tag == "new row")
                {
                    e.RowElement.DrawFill = true;
                    e.RowElement.BackColor = System.Drawing.Color.LightCyan;
                    e.RowElement.ForeColor = System.Drawing.Color.Black;
                    e.RowElement.Text = "New";
                    e.RowElement.TextAlignment = System.Drawing.ContentAlignment.TopLeft;
                }
                else if (e.RowElement is GridTableHeaderRowElement)
                {
                    e.RowElement.DrawFill = true;
                    e.RowElement.BackColor = System.Drawing.Color.Navy;
                    e.RowElement.NumberOfColors = 1;
                    e.RowElement.ForeColor = System.Drawing.Color.White;
                    e.RowElement.Text = "";
                }
                else
                {
                    e.RowElement.ResetValue(LightVisualElement.DrawFillProperty, Telerik.WinControls.ValueResetFlags.Local);
                    e.RowElement.ResetValue(LightVisualElement.BackColorProperty, Telerik.WinControls.ValueResetFlags.Local);
                    e.RowElement.ResetValue(LightVisualElement.NumberOfColorsProperty, Telerik.WinControls.ValueResetFlags.Local);
                    e.RowElement.ResetValue(LightVisualElement.ForeColorProperty, Telerik.WinControls.ValueResetFlags.Local);
                    e.RowElement.Text = "";
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Uncaught error in {System.Reflection.MethodBase.GetCurrentMethod().Name}: {ex.Message}");
            }
        }

 public partial class mainForm : Form
    {

        public static OleDbConnection con3 = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source = " + Application.StartupPath + "\\parts.accdb");
        public static DataTable dt = new DataTable();
        public OleDbDataAdapter adapter;
        public OleDbCommandBuilder commandbuider;
        public mainForm()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            string SQL = "SELECT * from supplier";
            adapter = new OleDbDataAdapter(SQL, con3);
            commandbuider = new OleDbCommandBuilder(adapter);

            adapter.Fill(dt);

            PartsGrid.DataSource = dt;

            PartsGrid.RowsChanged  += new GridViewCollectionChangedEventHandler(PartsGrid_Update);

        }

        private void PartsGrid_Update(object sender, GridViewCollectionChangedEventArgs e)
        {
            if (adapter.Update(dt) > 0)
            {
                MessageBox.Show("done");
            }
        }
    }