<connectionStrings>

    <add connectionString="Data Source=主机;Initial Catalog=数据库名;Persist Security Info=True;User ID=用户名;Password=密码" name="当前连接字符串名称"/>

  </connectionStrings>

    class SqlHelper

    {

        //获取连接字符串

        private readonly static string connectionStr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;

        /// <summary>

        /// 执行sql 增 删 该

        /// </summary>

        /// <param name="sql"></param>

        /// <param name="param"></param>

        /// <returns></returns>

        public static bool ExecuteNonQuery(string sql, params SqlParameter[] param)

        {

            int result;

            using (SqlConnection con = new SqlConnection(connectionStr))

            {

                using (SqlCommand cmd = new SqlCommand(sql, con))

                {

                    if (param != null)

                    {

                        cmd.Parameters.AddRange(param);

                    }

                    try

                    {

                        con.Open();

                        result = cmd.ExecuteNonQuery();

                    }

                    catch (Exception ex)

                    {

                        //如果连接失败，抛出异常，并手动释放资源

                        con.Close();

                        con.Dispose();

                        throw ex;

                    }

                }

                con.Close();

            }

            if (result == )

            {

                return true;

            }

            else

            {

                return false;

            }

        }

        /// <summary>

        /// 查询单行单列  或者是统计

        /// </summary>

        /// <param name="sql"></param>

        /// <param name="param"></param>

        /// <returns></returns>

        public static object ExecuteScalar(string sql, params SqlParameter[] param)

        {

            using (SqlConnection con = new SqlConnection(connectionStr))

            {

                using (SqlCommand cmd = new SqlCommand(sql, con))

                {

                    if (param != null)

                    {

                        cmd.Parameters.AddRange(param);

                    }

                    try

                    {

                        con.Open();

                        return cmd.ExecuteScalar();

                    }

                    catch (Exception ex)

                    {

                        //如果连接失败，抛出异常，并手动释放资源

                        con.Close();

                        con.Dispose();

                        throw ex;

                    }

                }

            }

        }

        /// <summary>

        /// 根据条件查询数据

        /// </summary>

        /// <param name="sql"></param>

        /// <param name="param"></param>

        /// <returns>SqlDataReader对象</returns>

        public static SqlDataReader ExecuteReader(string sql, params SqlParameter[] param)

        {

            using (SqlConnection con = new SqlConnection(connectionStr))

            {

                using (SqlCommand cmd = new SqlCommand(sql, con))

                {

                    if (param != null)

                    {

                        cmd.Parameters.AddRange(param);

                    }

                    try

                    {

                        con.Open();

                        return cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection);

                    }

                    catch (Exception ex)

                    {

                        //如果连接失败，抛出异常，并手动释放资源

                        con.Close();

                        con.Dispose();

                        throw ex;

                    }

                }

            }

        }

        /// <summary>

        /// 根据条件查询数据

        /// </summary>

        /// <param name="sql"></param>

        /// <param name="param"></param>

        /// <returns>DataTable对象</returns>

        public static DataTable ExcuteTable(string sql, params SqlParameter[] param)

        {

            using (SqlConnection con = new SqlConnection(connectionStr))

            {

                DataTable dt = new DataTable();

                using (SqlDataAdapter sda = new SqlDataAdapter(sql, connectionStr))

                {

                    if (param != null) {

                        sda.SelectCommand.Parameters.AddRange(param);

                    }

                    sda.Fill(dt);

                }

                return dt;

            }

        }

    }