[AttributeUsageAttribute(AttributeTargets.Class, Inherited = false, AllowMultiple = false)]
    public class TableAttribute : Attribute
    {
        //保存表名的字段
        private string _tableName;

public TableAttribute()
        {
        }

public TableAttribute(string tableName)
        {
            this._tableName = tableName;
        }

/// <summary>
        /// 映射的表名(表的全名:模式名.表名)
        /// </summary>
        public string TableName
        {
            set
            {
                this._tableName = value;
            }
            get
            {
                return this._tableName;
            }
        }
    }

User类

[Table("User")]
    public class User
    {
        [Colum("userID", DbType = DbType.Int32)]
        public int UserID { get; set; }
        [Colum("UserName", DbType = DbType.String)]
        public string UserName { get; set; }
    }

表特性
[AttributeUsageAttribute(AttributeTargets.Class, Inherited = false, AllowMultiple = false)]
    public class TableAttribute : Attribute
    {
        //保存表名的字段
        private string _tableName;

public TableAttribute()
        {
        }

public TableAttribute(string tableName)
        {
            this._tableName = tableName;
        }

/// <summary>
        /// 映射的表名(表的全名:模式名.表名)
        /// </summary>
        public string TableName
        {
            set
            {
                this._tableName = value;
            }
            get
            {
                return this._tableName;
            }
        }
    }

列特性
 [AttributeUsageAttribute(AttributeTargets.Property, Inherited = false, AllowMultiple = false)]
    public class ColumAttribute : Attribute
    {
        private string _columName;

private DbType _dbType ;

public ColumAttribute()
        {
        }

public ColumAttribute(string columName)
            : this()
        {
            this._columName = columName;
        }
     
        public ColumAttribute(string columName, DbType dbType)
            : this(columName)
        {
            this._dbType = dbType;
        }

//列名
        public virtual string ColumName
        {
            set
            {
                this._columName = value;
            }
            get
            {
                return this._columName;
            }
        }

//描述一些特殊的数据库类型
        public DbType DbType
        {
            get { return _dbType; }
            set { _dbType = value; }
        }

}

ORMHelp
 public class ORMHelp
    {
        public void Insert(object table)
        {
            Type type = table.GetType();
            //定义一个字典来存放表中字段和值的对应序列
            Dictionary<string, string> columValue = new Dictionary<string, string>();
            StringBuilder SqlStr=new StringBuilder();
            SqlStr.Append("insert into ");
            //得到表名子
            TableAttribute temp = (TalbeAttribute)type.GetCustomAttributes(typeof(TalbeAttribute), false).First();
            SqlStr.Append(temp.TableName);
            SqlStr.Append("(");
            PropertyInfo[] Propertys=type.GetProperties();
            foreach (var item in Propertys)
            {
                object[] attributes = item.GetCustomAttributes(false);
                foreach (var item1 in attributes)
                {
                    //获得相应属性的值
                   string value= table.GetType().InvokeMember(item.Name, System.Reflection.BindingFlags.GetProperty, null, table, null).ToString();
                    ColumAttribute colum = item1 as ColumAttribute;
                    if (colum != null)
                    {
                        columValue.Add(colum.ColumName,value);
                    }
                }
            }
            //拼插入操作字符串
            foreach (var item in columValue)
            {
                SqlStr.Append(item.Key);
                SqlStr.Append(",");

}
            SqlStr.Remove(SqlStr.Length-1, 1);
            SqlStr.Append(") values('");
            foreach (var item in columValue)
            {
                SqlStr.Append(item.Value);
                SqlStr.Append("','");

}
            SqlStr.Remove(SqlStr.Length - 2, 2);
            SqlStr.Append(")");
            Console.WriteLine(SqlStr.ToString());

}
    }

前端代码
static void Main(string[] args)
        {
            ORMHelp o = new ORMHelp();
            User u = new User() { UserID=1,UserName="lfm"};
            o.Insert(u);
        }