VB.net data update statement

Guys i am writing program, in which i have to insert data then update the data and then delete it,
now i am able to insert the data, but when i try to update i just retrive the data but when i try to change it , it gives me error, "Syntax error in update statement
Please help me if you can. thanks
Below is the code in which i got problem.

Imports System.Data
Imports System.Data.OleDb
Public Class DocChange
    Dim cnnOLEDB As New OleDbConnection
    Dim con As New OleDb.OleDbConnection
    Dim cn As OleDb.OleDbConnection

    Dim cmd As OleDbCommand
    Dim da As New OleDbDataAdapter
    
    Dim cmdOLEDB As New OleDbCommand

    Dim cmdInsert As New OleDbCommand

    Dim cmdUpdate As New OleDbCommand
    Dim str As String
    Dim cmdDelete As New OleDbCommand
    'Dim con As New OleDbConnection
    Dim dr As OleDbDataReader
    Dim sql As String
    Dim sql2 As String
    'Dim cmd As OleDbCommand
    Dim date1 As String
    Dim date2 As String
    Dim result As Integer
    Dim sql3 As String
    Dim sql4 As String
    'Dim cn As OleDb.OleDbConnection
    Dim strConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\My PC\Desktop\MOMS\MOMS\WindowsApplication2\MOMS.accdb"""

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddNew.Click
        DocAdd.Show()
        Me.Hide()
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnChange.Click
        Me.Show()
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
        DocDelete.Show()
        Me.Hide()
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEnquiry.Click
        DocEnquiry.Show()
        Me.Hide()

    End Sub

    Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnHome.Click
        Main_Menu.Show()
        Me.Hide()
    End Sub

    Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
        Application.Exit()
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnListing.Click
        DocListing.Show()
        Me.Hide()
    End Sub

    Private Sub DocChange_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    End Sub

    Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearch.Click

        Dim connectionStr As String
        connectionStr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\My PC\Desktop\MOMS\MOMS\WindowsApplication2\MOMS.accdb"
        sql = "Select * FROM Doctor WHERE DoctorID = @DoctorID"

        Dim cn As OleDbConnection = New OleDbConnection(connectionStr)


        cn.Open()
        cmd = New OleDbCommand(sql, cn)
        cmd.Parameters.AddWithValue("DoctorID", txtdoctorid.Text)
        Dim dr As OleDb.OleDbDataReader = cmd.ExecuteReader


        While (dr.Read())

            txtSurname.Text = dr.Item("Surname").ToString
            txtTitle.Text = dr.Item("Title").ToString
            txtAddress.Text = dr.Item("Address").ToString
            txtCityTown.Text = dr.Item("City Town").ToString
            txtState.Text = dr.Item("State").ToString
            txtZip.Text = dr.Item("zip").ToString
            txtRegNo.Text = dr.Item("RegNo").ToString
            txtPhoneNo.Text = dr.Item("Phone No").ToString
            txtMobileNo.Text = dr.Item("Mobile No").ToString
            txtUnitCode.Text = dr.Item("Unit Code").ToString
            txtCategory.Text = dr.Item("Category").ToString

        End While

        cn.Close()

    End Sub

    Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click
        Dim con As OleDbConnection
        Dim sql As String
        str = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\My PC\Desktop\MOMS 3\MOMS2\WindowsApplication2\MOMS.accdb"
        con = New OleDbConnection(str)
        'sql = "Update * FROM Doctor WHERE DoctorID = @DoctorID"
        'sql = "update students set name=’" & sname.Text & "‘,mobile=’" & mobile.Text & "‘,email=’" & email.Text & "‘ where roll=’" & roll.Text & "‘"
        ' sql = "UPDATE Doctor SET [Doc-ID]='" & txtdocid.Text & "‘,[Doc-Surname]=’" & txtdocsur.Text & "‘,[DocTitle]=’" & txtdoctitle.Text & "‘,[DocAddress]=’" & txtdocadd.Text & "‘,[DocCityTown]=’" & txtdoccity.Text & "‘,[DocState]=’" & txtdocstate.Text & "‘,[Doczip]=’" & txtdoczip.Text & "‘,[DocRegNo]=’" & txtdocreg.Text & "‘,[DocPhone1]=’" & txtdocphone.Text & "‘,[DocHandphone]=’" & txtdocmobile.Text & "‘,[DocUnitCode]=’" & txtdocunit.Text & "‘,[DocCategory]=’" & txtdoccat.Text & ""
        'sql = "UPDATE Doctor SET [Doc-ID] = @txtdocid , [Doc-Surname] = @txtdocsur , [DocTitle] = @txtdoctitle , [DocAddress] = @txtdocadd , [DocCityTown] = @txtdoccity , [DocState] = @txtdocstate , [Doczip] = @txtdoczip , [DocRegNo] = @txtdocreg , [DocPhone1] = @txtdocphone , [DocHandphone] = @txtdocmobile , [DocUnitCode] = @txtdocunit , [DocCategory] = @txtdoccat "
        sql = "UPDATE Doctor SET ([Doctor ID],[Surname],[Title],[Address],[City Town],[State],[Zip],[RegNo],[Phone No],[Mobile No],[Unit Code],[Category])values('" & txtdoctorid.Text & "', '" & txtSurname.Text & "', '" & txtTitle.Text & "', '" & txtAddress.Text & "', '" & txtCityTown.Text & "', '" & txtState.Text & "', '" & txtZip.Text & "', '" & txtRegNo.Text & "', '" & txtPhoneNo.Text & "', '" & txtMobileNo.Text & "', '" & txtUnitCode.Text & "', '" & txtCategory.Text & "')"

        Dim cmd As OleDbCommand
        Try
            con.Open()
            cmd = New OleDbCommand(sql, con)
            cmd.ExecuteScalar()
            MessageBox.Show("Update Successfully")
            con.Close()
            cmd.Dispose()
        Catch ex As OleDbException
            MsgBox(ex.Message, MsgBoxStyle.Critical, "Oledb Error")
        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.Critical, "General Error")
        End Try
    End Sub

    Private Sub txtSurname_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtSurname.TextChanged

    End Sub
End Class