castle ar 的update方法!!

有这么一个领域类
 public class Task    {
        private Project project;
        /// <summary>
        /// 项目
        /// int
        /// </summary>
        [BelongsTo("Project")]
        public Project Project
        {
            get { return project; }
            set { project = value; }
        }
        private IList childrens;
        [HasMany(typeof(Task), Table = "Task", ColumnKey = "ParentTask")]
        public IList Childrens
        {
            get { return childrens; }
            set { childrens = value; }
        }
        private Task parentTask;
        /// <summary>
        /// 父任务
        /// </summary>
        [BelongsTo("ParentTask")]
        public Task ParentTask
        {
            get { return parentTask; }
            set { parentTask = value; }
        }
       private IList members;
        [HasMany(typeof(Member), Table = "Member", ColumnKey = "Task")]
        public IList Members
        {
            get { return members; }
            set { members= value; }
        }

}
这里我关注 private IList childrens;,,就是因为有这样一个关系存在,当Task在做更新(update)时候,除了发生本身的一个update外,,还会根据此关系发生'UPDATE Task SET ParentTask = null WHERE ParentTask = @p0', N'@p0 int', @p0 = 327681,,,这是因为task与自己的子task有一对多关系!!!

以上是主外键在一个表时,,当主外在不同表中时,,比如上面的一个任务对应多个成员时,在更新任务后,也会紧紧跟一句生'UPDATE Member SET Task = null WHERE Task = @p0', N'@p0 int', @p0 = 327643,

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注意:
但是对于外键所在对象做更新时候,,,只更新自己,与其他对象不在发生任何联系