ช่วยหน่อยนะคะ SQLEXPRESS Update กับ Delete ไม่ได้คะ UPdate กับ Delete ไม่ได้คะ

Imports System.Data
Imports System.Data.SqlClient
Public Class Employee
    Private ConnectionString As String = "Data Source=TRUEFASTER\SQLEXPRESS;Initial Catalog=OrderingRestaurant;Integrated Security=True"
    Dim SqlConnection As New SqlConnection(ConnectionString)
    Dim SqlCommand As New SqlCommand
    Dim da As New SqlDataAdapter
    Dim IsFine As Boolean = False
    Dim btnChk As String


    Private Sub btnInsert_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnInsert.Click
        btnChk = "Add"   'เก็บการคิกปุ่มโดยให้มีค่าเป็นAdd
        btnInsert.Enabled = True  'ปุ่มเพิ่มปิดการทำงาน
        btnUpdate.Enabled = True  'ปุ่มแก้ไขปิดการทำงาน
        btnDelete.Enabled = True  'ปุ่มลบปิดการทำงาน
        btnSave.Enabled = True    'ปุ่มตกลงปิดการทำงาน
        btnCancel.Enabled = True  'ปุ่มยกเลิกปิดการทำงาน

        txtIDEmployee.Text = ""
        txtNameEmployee.Text = ""
        Sex.Text = ""
        txtAddress.Text = ""
        txtTel.Text = ""
        txtPass.Text = ""
        txtSalary.Text = ""
        txtemail.Text = ""
        txtPID.SelectedValue = ""
        txtNameEmployee.Focus() 'กำหนดให้ทำงานที่ txtNameEmployee

    End Sub

    Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
        If txtIDEmployee.Text = "" Or txtNameEmployee.Text = "" Or txtSalary.Text = "" Or txtAddress.Text = "" Or txtTel.Text = "" Or txtemail.Text = "" Then
            MessageBox.Show("กรุณากรอกข้อมุลพนักงานให้ครบ", "คำเตือน", MessageBoxButtons.OK, MessageBoxIcon.Warning)
        Else
            Try
                Dim SqlInsert As String = "INSERT INTO Employee(Employee_ID, Name, Sex, Salary, Address, Tel, Password, email, Position_ID) VALUES('" & txtIDEmployee.Text & "','" & txtNameEmployee.Text & "','" & Sex.Text & "','" & CInt(txtSalary.Text) & "','" & txtAddress.Text & "','" & CInt(txtTel.Text) & "','" & txtPass.Text & "','" & txtemail.Text & "','" & txtPID.SelectedValue & "')"

                Dim SqlConnection As New SqlConnection(ConnectionString)
                SqlConnection.Open()
                Dim SqlCommand As New SqlCommand(SqlInsert, SqlConnection)
                SqlCommand.ExecuteNonQuery()
                MessageBox.Show("เพิ่มข้อมูลเรียบร้อยแล้ว", "ผลการทำงาน")
                SqlConnection.Close()
                btnUpdate.Enabled = True
                btnDelete.Enabled = True
                ClearControl()
                RefreshDataGrid()
            Catch ex As Exception
                MessageBox.Show(ex.Message)
            End Try

        End If
        
    End Sub
    Private Sub ClearControl()
        txtIDEmployee.Text = ""
        txtNameEmployee.Text = ""
        Sex.Text = ""
        txtSalary.Text = ""
        txtAddress.Text = ""
        txtTel.Text = ""
        txtPass.Text = ""
        txtemail.Text = ""
        txtPID.Text = ""

    End Sub
    Private Sub RefreshDataGrid()
        Dim SqlOrderingRestaurant As String
        SqlOrderingRestaurant = "SELECT  Employee_ID, "
        SqlOrderingRestaurant &= "Name, Sex, "
        SqlOrderingRestaurant &= "Salary, Address, "
        SqlOrderingRestaurant &= "Tel, Password, "
        SqlOrderingRestaurant &= "email, "
        SqlOrderingRestaurant &= "Position_ID "
        SqlOrderingRestaurant &= "FROM Employee "


        If IsFine = True Then
            OrderingRestaurantDataSet.Tables("Employee").Clear()
        End If
        da = New SqlDataAdapter(SqlOrderingRestaurant, ConnectionString)
        da.Fill(OrderingRestaurantDataSet, "Employee")

        If OrderingRestaurantDataSet.Tables("Employee").Rows.Count <> 0 Then
            IsFine = True
            With DataGridView1
                .ReadOnly = True
                .DataSource = OrderingRestaurantDataSet.Tables("Employee")

            End With
        Else
            IsFine = False
        End If
    End Sub

    Private Sub btnUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnUpdate.Click
        btnChk = "Update"   'เก็บการคิกปุ่มโดยให้มีค่าเป็น Update
        txtIDEmployee.Text = ""
        txtNameEmployee.Text = ""
        Sex.Text = ""
        txtAddress.Text = ""
        txtTel.Text = ""
        txtSalary.Text = ""
        txtemail.Text = ""
        txtPID.Text = ""

    End Sub

    Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
        Dim SqlDelete As String
        Dim SqlConnection As New SqlConnection(ConnectionString)

        If MessageBox.Show("ต้องการลบข้อมูลนี้", "ยืนยัน", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) = Windows.Forms.DialogResult.OK Then
            'คำสั่งลบ SQL ตามคำสั่งพนักงาน
            SqlDelete = "DELETE FROM Employee"
            SqlDelete &= " WHERE(Employee_ID = '" & txtIDEmployee.Text & "')"

            Dim SqlCommand As New SqlCommand(SqlDelete, SqlConnection)
            SqlConnection.Open()

            With SqlCommand
                .CommandType = CommandType.Text
                .CommandText = SqlDelete
                .Connection = SqlConnection
                .ExecuteNonQuery()  ติดตรงนี้คะ


            End With
            SqlConnection.Close()
            MessageBox.Show("ลบข้อมูลเรียบร้อยแล้ว", "ผลกาารทำงาน", MessageBoxButtons.OK, MessageBoxIcon.Warning)
            ClearControl()
            RefreshDataGrid()

        End If
    End Sub

    Private Sub btnCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCancel.Click
        btnChk = ""                'เก็บค่าการคิกปุ่มโดยให้มีค่าเป็นค่าว่าง
        btnInsert.Enabled = True  'ปุ่มเพิ่มเปิดการทำงาน
        btnUpdate.Enabled = True  'ปุ่มแก้ไขเปิดการทำงาน
        btnDelete.Enabled = True  'ปุ่มลบเปิดการทำงาน
        btnSave.Enabled = True    'ปุ่มตกลงเปิดการทำงาน
        btnCancel.Enabled = True  'ปุ่มยกเลิกเปิดการทำงาน
    End Sub

    Private Sub Employee_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'TODO: This line of code loads data into the 'OrderingRestaurantDataSet.Position' table. You can move, or remove it, as needed.
        Me.PositionTableAdapter.Fill(Me.OrderingRestaurantDataSet.Position)
        'TODO: This line of code loads data into the 'OrderingRestaurantDataSet.DataTable1' table. You can move, or remove it, as needed.
        Me.DataTable1TableAdapter.Fill(Me.OrderingRestaurantDataSet.DataTable1)

    End Sub
End Class