Check duplicate value in Windows Form DataGridView column using VB.Net

Hi expertnandan22,

Refer below code

VB.Net

Protected Sub Form_Lodad(sender As Object, e As EventArgs) Handles Me.Load
    Dim dt As New DataTable()
    dt.Columns.AddRange(New DataColumn(1) {New DataColumn("Name"), New DataColumn("Country")})
    dt.Rows.Add("John Hammond", "United States")
    dt.Rows.Add("Mudassar Khan", "India")
    dt.Rows.Add("Suzanne Mathews", "France")
    dt.Rows.Add("Robert Schidner", "Russia")
    DataGridView1.DataSource = dt
End Sub

Private Sub OnVerify(sender As Object, e As EventArgs) Handles btnVerify.Click
    Dim Found As Boolean = False
    For i = 0 To Me.DataGridView1.Rows.Count - 1
        If Convert.ToString(Me.DataGridView1.Rows(i).Cells(1).Value) = "India" Then
            i = i + 1
            MsgBox("India found again", MsgBoxStyle.Information)
            Return
        End If
    Next
End Sub

Screenshot