风过无痕 原文 

 

深入理解游标Cursors，实现数据的快速查找，插入，删除，更新

1、查找数据Search Cursors

//by yl 2008.7.7

IEnvelope envelope = new EnvelopeClass();envelope.PutCoords(508786, 681196, 513033, 684341);ISpatialFilter spatialFilter = new SpatialFilterClass();spatialFilter.Geometry = envelope;String shpFld = featureClass.ShapeFieldName;spatialFilter.GeometryField = shpFld;spatialFilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelIntersects;IQueryFilter queryFilter = new QueryFilterClass();queryFilter = (IQueryFilter)spatialFilter;IFeatureCursor searchCursor = featureClass.Search(queryFilter, true);//只查询，true快一些IFeature feature = searchCursor.NextFeature();int n = 0;while (feature != null){    n++;    feature = baseCursor.NextFeature();}

 

 

2、插入数据Insert Cursors—目前数据插入最快的方法   

//by yl 2008.7.7

IFeatureBuffer featureBuffer = featureClass.CreateFeatureBuffer();IFeatureCursor featureCursor = featureClass.Insert(true);object featureOID;         featureBuffer.set_Value(featureBuffer.Fields.FindField("InstBy"), "B Pierce");for (int ic = 0; ic < 99; ic++) {         featureBuffer.Shape = geometry   featureOID = featureCursor.InsertFeature(featureBuffer);}featureBuffer.set_Value(featureBuffer.Fields.FindField("InstBy"), "K Johnston");for (int ic = 0; ic < 99; ic++){     featureBuffer.Shape = geometry     featureOID = featureCursor.InsertFeature(featureBuffer);}featureCursor.Flush();

 

3、 数据删除 delete   

//by yl 2008.7.7

IFeatureClass featureClass = featureWorkspace.OpenFeatureClass("Parcels"); IQueryFilter queryFilter = new QueryFilterClass();queryFilter.WhereClause = "ZONING_S = 'R'";IFeatureCursor updateCursor = featureClass.Update(queryFilter, false);IFeature feature = updateCursor.NextFeature(); int m = 0;while (feature != null){    m++;    updateCursor.DeleteFeature(feature);    feature = updateCursor.NextFeature();}

 

 

4、数据更新 update   

 

//by yl landgis@126.com yanleigis@21cn.com 2008.7.7IFeatureClass featureClass = featureWorkspace.OpenFeatureClass("Parcels");// restrict the number of features to be updated.IQueryFilter queryFilter = new QueryFilterClass();queryFilter.WhereClause = "ZONING_S = 'U'"; // use IFeatureClass::Update to populate IFeatureCursorIFeatureCursor updateCursor = featureClass.Update(queryFilter, false);int fieldindex = featureClass.FindField("ZONING_S");IFeature feature = updateCursor.NextFeature();int m = 0;while (feature != null){    m++;    feature.set_Value(fieldindex, "X");    updateCursor.UpdateFeature(feature);    feature = updateCursor.NextFeature();}