提示出错：索引超出范围 。 datagrid怎么删除？

[zwbwork]

public sqlserver as string
Sqlserver = "server=PTG07;database=OMS;uid=sa;pwd="
页面上有一个名为memberdata 的datagrid控件,给它加了编辑、删除按钮

Private Sub memberdata_DeleteCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs) Handles memberdata.DeleteCommand
Dim delCommand As SqlClient.SqlCommand
Dim delStr As String
Dim conn As SqlClient.SqlConnection
conn = New SqlClient.SqlConnection(Sqlserver)
conn.open()

delStr = "Delete from customer Where customerid = @customerid"
'表customer有关键字段customerid

delCommand = New SqlClient.SqlCommand(delStr, conn)
delCommand.Parameters.Add(New SqlClient.SqlParameter("@customerid", SqlDbType.NVarChar, 50))

delCommand.Parameters.Item("@customerid").Value = memberdata.DataKeys.Item(e.Item.ItemIndex)
'运行到此提示出错：索引超出范围。必须为非负值并小于集合大小。参数名: index

delCommand.ExecuteReader()
memberdata.EditItemIndex = -1
BindMemberData() '显示数据
End Sub
问题:
1 为什么会出现“索引超出范围”这种错，我是照一本书上写的，错在哪里了？
2 这个程序怎么写我才能达到删除的目的？
3 怎么才能得到我点击的datagrid的某行某列的值？

[zhanggy1973]

是因为datagrid没设datafieldkey的值所致

[brightheroes]

delCommand.Parameters.Item("@customerid").Value = memberdata.DataKeys.Item(e.Item.ItemIndex)

--->

delCommand.Parameters.Item("@customerid").Value = memberdata.DataKeys(e.Item.ItemIndex).ToString()

[fencunzhijian]

楼上的回答正确