how to move to next row in datagridview in vb.net

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VB

I have datagridview which contains 12 columns.Last 3 columns are caste,prof,degree and these are comboboxcolumn. I am changing these comboboxcolumn values to save it into database.
On cellvalue changed event,I am writing following code:

If e.ColumnIndex = 9 Then
            If Me.dgvUserDetails.Rows(e.RowIndex).Cells(9).Value.ToString <> "" Then
                caste = Me.dgvUserDetails.Rows(e.RowIndex).Cells(9).Value.ToString
                sql = "Select ID from Category where Desc = '" & caste & "'"
                If rs.State = 1 Then rs.Close()
                rs.Open(sql, MainCon, 1, 3)
                If Not rs.EOF Then
                    C_Id = rs.Fields(0).Value
                End If
                
            End If
        ElseIf e.ColumnIndex = 10 Then
            If Me.dgvUserDetails.Rows(e.RowIndex).Cells(10).Value.ToString <> "" Then
                prof = Me.dgvUserDetails.Rows(e.RowIndex).Cells(10).Value.ToString
                sql = "Select ID from Category where Desc = '" & prof & "'"
                If rs.State = 1 Then rs.Close()
                rs.Open(sql, MainCon, 1, 3)
                If Not rs.EOF Then
                    P_Id = rs.Fields(0).Value
                End If
               
            End If
        ElseIf e.ColumnIndex = 11 Then
            If Me.dgvUserDetails.Rows(e.RowIndex).Cells(11).Value.ToString <> "" Then
                degree = Me.dgvUserDetails.Rows(e.RowIndex).Cells(11).Value.ToString
                sql = "Select ID from Category where Desc = '" & degree & "'"
                If rs.State = 1 Then rs.Close()
                rs.Open(sql, MainCon, 1, 3)
                If Not rs.EOF Then
                    D_Id = rs.Fields(0).Value
                End If
                
            End If
        End If

I want to use for loop to move to next row.How to use it?