datagridview insert, update

Public Class frmPrincipal

    Dim strConexao As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=" & Environment.CurrentDirectory & "\grid.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True"
    Dim isNovo As Boolean = False

    Private Sub frmPrincipal_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        grid1.Columns.Add("colId", "Id")
        grid1.Columns.Add("colNome", "Nome")
        grid1.Columns.Add("colNumero", "Numero")
        grid1.Columns(0).ReadOnly = False
        preencherDados(grid1)
    End Sub

    Public Sub adicionar(nome As String, numero As Integer)
        Dim conexao As SqlConnection = New SqlConnection(strConexao)
        Dim Comando As SqlCommand = New SqlCommand("INSERT INTO Teste(Nome, Numero) Values ('" & nome & "','" & numero & "')", conexao)
        Try
            conexao.Open()
            Comando.ExecuteNonQuery()
            conexao.Close()
        Catch ex As SqlException
            MsgBox(ex.Message)
        End Try

    End Sub

    Public Sub atualizar(id As Integer, nome As String, numero As Integer)
        Dim conexao As SqlConnection = New SqlConnection(strConexao)
        Dim Comando As SqlCommand = New SqlCommand("UPDATE Teste Set Nome = '" & nome & "', Numero = '" & numero & "' WHERE id = " & id, conexao)
        Try
            conexao.Open()
            Comando.ExecuteNonQuery()
            conexao.Close()
        Catch ex As SqlException
            MsgBox(ex.Message)
        End Try

    End Sub

    Public Sub preencherDados(grid As DataGridView)

        Dim conexao As SqlConnection = New SqlConnection(strConexao)
        Dim comando As SqlCommand = New SqlCommand("SELECT * FROM Teste", conexao)
        Dim dr As SqlDataReader

        Try
            conexao.Open()
            dr = comando.ExecuteReader
            Do While dr.Read
                grid1.Rows.Add(dr(0).ToString, dr(1).ToString, dr(2).ToString)
            Loop
            dr.Close()
            conexao.Close()
        Catch ex As SqlException
            MsgBox(ex.Message)
        End Try
    End Sub

    Private Sub grid1_CellBeginEdit(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellCancelEventArgs) Handles grid1.CellBeginEdit
        If grid1.CurrentRow.IsNewRow Then
            isNovo = True
        End If
    End Sub

    Private Sub grid1_RowValidated(sender As Object, e As System.Windows.Forms.DataGridViewCellEventArgs) Handles grid1.RowValidated
        isNovo = False
    End Sub

    Private Sub grid1_RowValidating(sender As Object, e As System.Windows.Forms.DataGridViewCellCancelEventArgs) Handles grid1.RowValidating
        If grid1.IsCurrentRowDirty Then
            grid1.CommitEdit(DataGridViewDataErrorContexts.Commit)
            If isNovo = True Then
                adicionar(grid1.Rows(e.RowIndex).Cells("colNome").Value, grid1.Rows(e.RowIndex).Cells("colNumero").Value)
            Else
                atualizar(grid1.Rows(e.RowIndex).Cells("colId").Value, grid1.Rows(e.RowIndex).Cells("colNome").Value, grid1.Rows(e.RowIndex).Cells("colNumero").Value)
            End If
        End If
    End Sub

    Public Sub removeRows(grid As DataGridView)
        If grid1.Rows.Count > 0 Then
            For Each dr As DataGridViewRow In grid.Rows
                If Not dr.IsNewRow Then grid.Rows.Remove(dr)
            Next
        End If
    End Sub

    
End Class