How to avoid duplicate entries in database access - vb.net

Question

I'm creating a Registration form
How can i Prevent a data from duplicating when i save a data to my Ms access Database , something like Error handling for duplicate data or same First Name/Last Name and a message box that says there's a duplicated data.
As for now this is the code that i saw someone uses.
For i As Integer = 0 To DataGridView1.Rows.Count - 1
If Fname.Text = DataGridView1.Rows(i).Cells(0).Value.ToString() Then
MessageBox.Show("Duplicate Info")
Return
End If
Next
Do you guys have any suggestion , Thanks in Advance

Answer 1

This might be useful for what you asked, but personally I would check if Data matches the one in DB instead of DataGridView, because Users can edit them if you don't set ReadOnly property to true.
Private Sub DuplicatePrevention(datagridview As DataGridView, name As String)
Dim duplicateCount As Integer = 0
For i As Integer = 0 To datagridview.Rows.Count - 1
If datagridview.Rows(i).Cells(0).Value.ToString = name Then
duplicateCount += 1
End If
Next
If duplicateCount = 0 Then
'fire your Query
Else
MsgBox(name & " exist already", MsgBoxStyle.Information)
End If
End Sub