SQLCommon封装基础查询方法

        /// <summary>
        /// 单一结果查询
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static int ExecuteNonQuery(string sql)
        {
            SqlConnection conn = new SqlConnection(connString);
            SqlCommand cmd = new SqlCommand(sql, conn);

            try
            {
                conn.Open(); 
                return cmd.ExecuteNonQuery();
            }
            catch (Exception ex)
            {

                throw;
            }
            finally { conn.Close(); }
        }

        /// <summary>
        /// 单行查询
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static Object ExecuteScalar(string sql)
        {
            SqlConnection conn = new SqlConnection(connString);
            SqlCommand cmd = new SqlCommand(sql, conn);

            try
            {
                conn.Open();
                return cmd.ExecuteScalar();
            }
            catch (Exception ex)
            {
                throw;
            }
            finally { conn.Close(); }
        }

        /// <summary>
        /// 单表查询Adapter
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static DataTable GetDataTable(string sql)
        {
            SqlConnection conn = new SqlConnection(connString);
            SqlCommand cmd = new SqlCommand(sql, conn);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();

            try
            {
                conn.Open();
                da.Fill(dt);
                return dt;
            }
            catch (Exception ex)
            {

                throw;
            }
            finally { conn.Close() ; }
        }

        /// <summary>
        /// Reader
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static SqlDataReader GetReader(string sql)
        {
            SqlConnection conn = new SqlConnection();
            SqlCommand cmd = new SqlCommand(sql, conn);

            try
            {
                conn.Open();
                return cmd.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch (Exception ex)
            {

                throw;
            }
        }