รบกวนสอบถามเรื่องการลบข้อมูลใน grid view โดยใช้ check box จากหลายตาราง

Imports Microsoft.VisualBasic
Imports System
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.Configuration
Imports System.Web.UI.WebControls

Partial Public Class HR_1
    Inherits System.Web.UI.Page
    Dim conn As SqlConnection
    Dim cmd As SqlCommand
    Dim strConn As String
    Dim strSql As String

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim strTest1 As String = Request.QueryString("abc")
        Response.Write(strTest1)

        strConn = WebConfigurationManager.ConnectionStrings("connects").ConnectionString
        conn = New SqlConnection(strConn)
        conn.Open()

        btnDelete.Attributes.Add("onClick", "javascript:return confirm('Are you sure you want to delete to delete these rows?')")
        If Not Page.IsPostBack() Then
            DataBind()
        End If

        Dim strSql As String
        strSql = "SELECT employee.employee_id, employee.username, employee.password, employee.first_name, employee.last_name, employee.email, department.depertment_name, roces_role.access_level_name, employee_authentication.authentication_name, employee_head.employee_head_name, center.center_name_middle FROM employee INNER JOIN employee_authentication ON employee.authentication_id = employee_authentication.authentication_id INNER JOIN employee_head ON employee.employee_head_id = employee_head.employee_head_id INNER JOIN roces_role ON employee.access_level_id = roces_role.access_level_id INNER JOIN department ON employee.department_id = department.department_id INNER JOIN center ON department.center_id = center.center_id"
        Dim da As New SqlDataAdapter(strSql, conn)
        Dim ds As New DataSet
        da.Fill(ds, "employee")

        gvEmployee.DataSource = ds.Tables("employee")
        gvEmployee.DataBind()

    End Sub

    Protected Sub btnDelete_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnDelete.Click
        Dim chkbox As CheckBox = New CheckBox

        For Each grdRow As GridViewRow In gvEmployee.Rows
            chkbox = CType(grdRow.FindControl("chkItem"), CheckBox)
            If chkbox.Checked Then
                Dim employee_id As String = gvEmployee.DataKeys(grdRow.RowIndex).Value.ToString
                Dim department_name As String = gvEmployee.DataKeys(grdRow.RowIndex).Value.ToString
                Dim center_name As String = gvEmployee.DataKeys(grdRow.RowIndex).Value.ToString
                Dim authentication_name As String = gvEmployee.DataKeys(grdRow.RowIndex).Value.ToString
                Dim employee_head_name As String = gvEmployee.DataKeys(grdRow.RowIndex).Value.ToString
                Dim access_level_name As String = gvEmployee.DataKeys(grdRow.RowIndex).Value.ToString
                SDSEmployee.DeleteParameters("employee_id").DefaultValue = employee_id
                SDSEmployee.DeleteParameters("department_name").DefaultValue = department_name
                SDSEmployee.DeleteParameters("center_name").DefaultValue = center_name
                SDSEmployee.DeleteParameters("authentication_name").DefaultValue = authentication_name
                SDSEmployee.DeleteParameters("employee_head_name").DefaultValue = employee_head_name
                SDSEmployee.DeleteParameters("access_level_name").DefaultValue = access_level_name
                SDSEmployee.Delete()
            End If
        Next
        gvEmployee.DataBind()
    End Sub

End Class