[RESOLVED] How to validate data on datagridview to prevent duplicate

for example i have "NID" as textbox and datagrid with @NID field.
i want save NID with Value "N001" to @NID on datagrid.
how to prevent duplicate when i save NID with value "N001" to datagrid.

I trying like this but error :

Code:

---

private sub save() 
dim dgv as datagridview1 
if dgv.CurrentRow.Cells(0).value = NID.text then 
msgbox("Data duplicate") 
else 
dgv.rows.insert(.NewRowIndex, NID.text) 
end if 
end sub

---

help me
thanks

vb.net Code:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim Exists As Boolean = False
        For Each item As DataGridViewRow In DataGridView1.Rows
            If item.Cells(0).Value = NID.Text Then
                Exists = True
            End If
        Next
        If DataGridView1.Rows.Count > 0 AndAlso Exists = True Then
            MsgBox("Data duplicate")
            Exit Sub
        Else
            DataGridView1.Rows.Insert(DataGridView1.NewRowIndex, NID.Text)
        End If
    End Sub

Problem solved ...
I used this code -->

Code:

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For i As Integer = 0 To dataspdibeli.Rows.Count - 1
            If Not IsDBNull(dataspdibeli.Rows(i).Cells("NID_SP").Value) AndAlso dataspdibeli.Rows(i).Cells("NID_SP").Value = spnid.Text Then

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thanks <-_->
#junior_programmer