how to update the each gridview rows with a single of click button and update in the database

int i = 0;
            int j = 0;
            con = new OleDbConnection("YourConnectionString");//Which ever connection you are using
            con.Open();
            while (i < dataGridView1.Rows.Count)
            {
                string str = "update YourTableName set YourColumnName='" + dataGridView1.Rows[1].Cells[i].Value + "' where RommNo='" + dataGridView1.Rows[0].Cells[i].Value + "'";//you update query
                cmd = new OleDbCommand(str(), con);
                cmd.ExecuteNonQuery();
                i += 1;
            }
            i = 0;
            while (i < DataGridView1.Rows.Count)
            {
                str() = "update YourTableName set YourColumnName='" + dataGridView1.Rows[3].Cells[i].Value + "' where RommNo='" + dataGridView1.Rows[2].Cells[i].Value + "'";//Your update query
                cmd = new OleDbCommand(str(), con);
                cmd.ExecuteNonQuery();
                i += 1;
            }