EF 更新部分字段写法

      　　　 db.Set<T>().Attach(entity);//将数据用未更改的状态放在上下文中，相当于从数据库读取了该实体

            var loginUser = GetLoginUser();
            entity.ModifyDate = DateTime.Now;
            entity.ModifyId = loginUser.Id;
            entity.ModifyName = loginUser.UserName;

            db.Entry(entity).State = EntityState.Modified;
            db.Entry(entity).Property("CreateId").IsModified = false;
            db.Entry(entity).Property("CreateName").IsModified = false;
            db.Entry(entity).Property("CreateDate").IsModified = false;

           db.SaveChanges();

using EntityFramework.Extensions;

  db.Set<SysRole>().Where(c => c.Id == sysRole.Id)
                            .Update(c => new SysRole
                                {
                                    RoleName = sysRole.RoleName,
                                    Level = sysRole.Level,
                                    ModifyDate = DateTime.Now,
                                    ModifyId = loginUser.Id,
                                    ModifyName = loginUser.UserName
                                });