C# SQL 公用类

        public  static SqlConnection Conn;
        public static SqlCommand cmmd;
        public static DataTable dt;
        public static DataSet ds;
        public static SqlDataAdapter da;

        private static string sqlstr = ConfigurationManager.ConnectionStrings["conn"].ConnectionString;//从配置哪里获取sql连接方法

        SqlConnection conn = new SqlConnection(sqlstr); //初始化SqlConnection

        /// <summary>
        /// 执行一个sql语句，返回第一行第一个值
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static object GetFirstValue(string sql)
        {
            using (Conn= new SqlConnection(sqlstr))
            {
                Conn.Open();
                cmmd = new SqlCommand(sql, Conn);
                return cmmd.ExecuteScalar();
            }
        }
        /// <summary>
        /// 执行一个sql语句，返回受影响行数
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static int GetNonQuery(string sql)
        {
            using (Conn= new SqlConnection(sqlstr))
            {
                Conn.Open();
                cmmd = new SqlCommand(sql, Conn);
                return cmmd.ExecuteNonQuery();
            }
        }
        /// <summary>
        /// 离线模式填充datatable并返回，数据少可以用此方法
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static DataTable GetDataTableA(string sql)
        {
            using (Conn= new SqlConnection(sqlstr))
            {
                da = new SqlDataAdapter(sql, Conn);
                dt = new DataTable();
                da.Fill(dt);
                return dt;
            }
        }

        /// <summary>
        /// 根据sql,填充datatable并返回。数据多的时候可以用此方法
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static DataTable GetDataTableB(string sql)
        {
            using (Conn= new SqlConnection(sqlstr))
            {
                Conn.Open();
                cmmd = new SqlCommand(sql, Conn);
                dt = new DataTable();
                SqlDataReader reader = cmd.ExecuteReader();
                dt.Load(reader);
                Conn.Close();
                return dt;
            }
        }
        /// <summary>
        /// 传入sql语句集，返回一个dataset
        /// </summary>
        /// <param name="sqllist"></param>
        /// <returns></returns>
        public static DataSet GetDataSet(List<string> sqllist)
        {
            using (Conn= new SqlConnection(sqlstr))
            {
                Conn.Open();
                ds = new DataSet();
                foreach (string c in sqllist)
                {
                    cmmd = new SqlCommand(c, Conn);
                    dt = new DataTable();
                    SqlDataReader reader = cmmd.ExecuteReader();
                    dt.Load(reader);
                    ds.Tables.Add(dt);
                }
                Conn.Close();
                return ds;
            }
        }
        /// <summary>
        /// 在事务中执行多条sql语句
        /// </summary>
        /// <param name="list"></param>
        /// <returns></returns>
        public static bool ExecSQLSList(List<string> list)
        {
            using (Conn= new SqlConnection(sqlstr))
            {
                Conn.Open();
                SqlTransaction tran = Conn.BeginTransaction();
                try
                {
                    foreach (string sql in list)
                    {
                        cmmd = new SqlCommand(sql, Conn);
                        cmmd.ExecuteNonQuery();
                    }
                    tran.Commit();
                    Conn.Close();
                    return true;

                }
                catch
                {
                    tran.Rollback();
                    return false;
                }
                finally
                {
                    Conn.Close();
                    Conn.Dispose();
                }
            }

        }


        /// <summary>
        /// 执行一个不带参数的存储过程，返回datable
        /// </summary>
        /// <param name="StoredProcedureName"></param>
        /// <returns></returns>
        public static DataTable GetDataTableByStoredProcedure(string StoredProcedureName)
        {
            using (Conn= new SqlConnection(sqlstr))
            {
                Conn.Open();
                cmmd = new SqlCommand();
                cmmd.CommandText = StoredProcedureName;
                cmmd.CommandType = CommandType.StoredProcedure;
                dt = new DataTable();
                dt.Load(cmmd.ExecuteReader());
                return dt;
            }
        }
//app.confine 陪着代码
  <connectionStrings>
    <add name="conn" connectionString="Data Source=110.110.110.110;Initial Catalog=alipay;Persist Security Info=True;User ID=sa;Password=123456" providerName="System.Data.SqlClient"/>
  </connectionStrings>

个人备用。有喜欢的同学可以拿去！！！ 这个是winform。注意要去APP.confine 进行配置