zoukankan      html  css  js  c++  java
  • What is the difference between searching a featurelcass versus a featurelayer?

    What is the difference between searching a featurelcass versus a featurelayer?

    IFeatureClass.Search:

         Returns an object cursor that can be used to fetch feature objects selected by the specified query.

    IFeatureLayer2.Search:

         Use this method to return a read-only cursor of the layer’s features.

    There is ‘Search; method in both IFeatureLayer and IFeatureClass Interface. Both returns cursor based on search criteria(标准、尺度). What is difference between these?. This question is obivious for a novice(新手). If you have gone through Help documentation you can figure out easily. Else here is a straight answer

    They are the same unless you have a definition query assigned to the layer. In that case the FeatureLayer.Search will only return features that also meet the definition query criteria, while FeatureClass.Search will return all features regardless of definition query. 

    This FeatureLayer Search method will not work on joined fields. If the FeaureLayer has any joins, you should use the IGeoFeatureLayer::SeachDisplayFeatures method instead.

    You cannot use the cursor returned by IFeatureLayer::Search to update features, instead use IFeatureClass::Update.

    -----------------------------------------------------------------------------------------------------------------------------------------------

    1、FeaturLayer是加载在地图文档中的数据层,只是要素类的表现形式;FeatureClass是一组空间实体的集合,在数据表中存储了统一的属性和行为,每一个FeatureClass都有一个Geometry类型,如shp文件;

    2、IFeatureLayer继承自ILayer,IFeatureClass继承自IClass;

    3、FeatureLayer可以创建自己的对象,而FeatureClass不行:

    IFeatureClass=IFeatureLayer.FeatureClass 或者

    IFeatureClass=IFeatureWorkspace.openFeatureClass("xx")


  • 相关阅读:
    JavaBean理解
    你应该掌握的七种回归技术
    回归分析步骤
    rsync命令(同步/备份数据)
    获取客户端访问的ip地址
    SSO单点登陆
    产品分类之属性选择
    linux的SVN搭建与同步
    php 实现 mysql数据表优化与修复
    php程序备份还原mysql数据库
  • 原文地址:https://www.cnblogs.com/xingchen/p/1989884.html
Copyright © 2011-2022 走看看