public static DataSet GetDataSet(string stringSql)

        {

            DataSet ds = new DataSet();

            using (SqlConnection conn = new SqlConnection(connectionString))

            {

                SqlDataAdapter adapter = new SqlDataAdapter();

                adapter.SelectCommand = new SqlCommand(stringSql, conn);

                adapter.Fill(ds);

            }

            return ds;

        }

        public static int ExecuteScalar(string stringSql)

        {

            using (SqlConnection conn = new SqlConnection(connectionString))

            {

                using (SqlCommand cmd = new SqlCommand(stringSql, conn))

                {

                    try

                    {

                        conn.Open();

                        object obj = cmd.ExecuteScalar();

                        int i = Convert.ToInt32(obj);

                        return i;

                    }