บันทึกข้อมูลได้ แต่แก้ไขข้อมูลไม่ได้ครับ มือใหม่มากๆ

Imports System.Data
Imports System.Data.OleDb
Public Class Rests
    Dim status As String
    Public sendVar As String
    Public Sub Showdata()
        Dim Con As OleDbConnection
        Dim dtAdapter As OleDbDataAdapter
        Dim dt As New DataTable
        Dim Str As String
        Str = "SELECT * FROM Rest,Student,Patients WHERE Rest.Student_ID = Student.Student_ID AND Rest.Patients_ID = Patients.Patients_ID"

        Connection(Con)
        dtAdapter = New OleDbDataAdapter(Str, Con)
        dtAdapter.Fill(dt)

        Con.Close()
        dtAdapter = Nothing
        Con = Nothing

        


    End Sub
    Private Sub add_Student()
        Dim objConn As New OleDbConnection
        Dim dtAdapter As OleDbDataAdapter
        Dim ds As New DataSet
        Dim strSQL As String
        Connection(objConn)
        strSQL = "SELECT * FROM Student"

        dtAdapter = New OleDbDataAdapter(strSQL, objConn)
        dtAdapter.Fill(ds)
        With TextBox1.Text

        End With
        TextBox1.Text = 1
    End Sub
    Private Sub add_Bag()
        Dim objConn As New OleDbConnection
        Dim dtAdapter As OleDbDataAdapter
        Dim ds As New DataSet
        Dim strSQL As String
        Connection(objConn)
        strSQL = "SELECT * FROM Patients"

        dtAdapter = New OleDbDataAdapter(strSQL, objConn)
        dtAdapter.Fill(ds)
        With ComboBox1
            .DataSource = ds.Tables(0)
            .DisplayMember = "Patients_name"
            .ValueMember = "Patients_ID"
        End With
        ComboBox1.SelectedItem = 1
    End Sub

    Public Sub Disable()
        TextBox1.Enabled = False
        TextBox2.Enabled = False
        ComboBox1.Enabled = False
        DateTimePicker1.Enabled = False


    End Sub
    Public Sub Enable()
        TextBox2.Enabled = True
        ComboBox1.Enabled = True
        DateTimePicker1.Enabled = True

    End Sub
    Public Sub Clear()
        TextBox2.Text = ""
        TextBox1.Text = ""
        ComboBox1.Text = ""
        DateTimePicker1.Text = ""
    End Sub
    Private Sub Test_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Disable()
        Showdata()
        add_Bag()
    End Sub
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Enable()
        status = "add"
    End Sub
    Public Shared OID As String
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Clear()
        Disable()
        status = ""
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        Dim Conn As New OleDbConnection
        Dim Cmd As New OleDbCommand
        Dim Str As String = ""

        If status = "add" Then

            Str = "INSERT INTO Rest(Student_ID,Patients_ID,Date_of_rest) VALUES("

            Str &= "" & TextBox2.Text & ","
            Str &= "'" & ComboBox1.SelectedValue.ToString & "', "
            Str &= "'" & DateTimePicker1.Text & "'"
            Str &= ")"

        ElseIf status = "edit" Then

            Str = "UPDATE Rest SET "
            Str &= "Student_ID=" & TextBox2.Text & ","
            Str &= "Patients_ID=" & ComboBox1.SelectedValue.ToString & ","
            Str &= "Date_of_rest='" & DateTimePicker1.Text & "'"
            Str &= "WHERE Date_of_rest=" & TextBox1.Text & ""
        ElseIf status = "del" Then

            Str = "DELETE Rest WHERE Rest_ID=" & TextBox1.Text & ""
        End If



        Try
            Connection(Conn)
            Cmd = New OleDbCommand(Str, Conn)
            Cmd.ExecuteNonQuery()
            Conn.Close()
        Catch ex As Exception
            MsgBox("Error")
        End Try


        Showdata()
        Clear()
        Disable()
        status = ""

    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        status = "del"
        If MsgBox("แน่ใจหรือไม่ว่าต้องการลบข้อมูล", MsgBoxStyle.OkCancel, "ตกลง") = MsgBoxResult.Ok Then
            Dim Conn As New OleDbConnection
            Dim Cmd As New OleDbCommand
            Dim Str As String = "DELETE FROM Rest WHERE Rest_ID=" & TextBox1.Text & ""

            Connection(Conn)
            Cmd = New OleDbCommand(Str, Conn)
            Cmd.ExecuteNonQuery()
            Conn.Close()

            Showdata()
            Clear()
            Disable()
            status = ""

        End If
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        status = "edit"
        Enable()
        TextBox1.Enabled = False
    End Sub
    Private Sub DataGridView1_CellDoubleClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellDoubleClick
        TextBox1.Text = DataGridView1.Rows(e.RowIndex).Cells(0).Value.ToString
        TextBox2.Text = DataGridView1.Rows(e.RowIndex).Cells(1).Value.ToString
        ComboBox1.Text = DataGridView1.Rows(e.RowIndex).Cells(2).Value.ToString
        DateTimePicker1.Text = DataGridView1.Rows(e.RowIndex).Cells(3).Value.ToString

    End Sub

End Class