ArcGIS Engine开发Geodatabase代码（四）——Join

/******************************************/
 * ESRI Developer Summit 2009
 * Developer's Guide to the Geodatabase
 * Code Samples
 * 6 April 2009
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偶然间整理电脑的文件夹，发现在Esri官网上曾经下载过关于Geodatabase开发的相关代码示例，赶紧跟各位共享一下
开发环境：

• ArcGIS Engine9.3/9.3.1
• VS2008

说明：该代码适用于ArcGIS Engine初学者，或者对Geodatabase开发感兴趣的朋友，如果你的Engine版本高于9.3.1，可能相关的接口会发生变化，这个需要用户自己来进行修改，但是聪明的用户不会局限于代码的是否允许，也许学习一下人家的接口使用方法，开发模式才是最重要的。
关于版本的接口差别参考：http://help.arcgis.com/en/sdk/10.0/arcobjects_net/conceptualhelp/index.html#/Type_changes_between_9_3_and_10/000100000408000000/

在我们使用过程中，经常使用Join进行连接，以下代码就是来实现join功能

using System;
using System.Runtime.InteropServices;
using ESRI.ArcGIS.ADF;
using ESRI.ArcGIS.esriSystem;
using ESRI.ArcGIS.Geodatabase;
using ESRI.ArcGIS.Geometry;

namespace JoinDemo
{
	public class JoinDemo
	{
		public static void Main(string[] args)
		{
			#region Licensing
			// Set up the licencing. NOTE: This sample assumes that you are using ArcInfo Desktop.
			// You will need to adjust this code if using ArcEngine or ArcEditor.
			IAoInitialize aoInitialize = new AoInitializeClass();
			esriLicenseStatus licenseStatus = aoInitialize.Initialize(esriLicenseProductCode.esriLicenseProductCodeArcInfo);
			if (licenseStatus != esriLicenseStatus.esriLicenseCheckedOut)
			{
				Console.WriteLine("Unable to check-out an ArcInfo license, error code is {0}", licenseStatus);
				return;
			}
			#endregion

			// Open the File Geodatabase and the Parcels feature class.
			Type fgdbFactoryType = Type.GetTypeFromProgID("esriDataSourcesGDB.FileGDBWorkspaceFactory");
			IWorkspaceFactory fgdbWorkspaceFactory = (IWorkspaceFactory)Activator.CreateInstance(fgdbFactoryType);
			IWorkspace fgdbWorkspace = fgdbWorkspaceFactory.OpenFromFile(@"..\..\..\Data\JoinDemo.gdb", 0);
			IFeatureWorkspace fgdbFeatureWorkspace = (IFeatureWorkspace)fgdbWorkspace;
			IFeatureClass featureClass = fgdbFeatureWorkspace.OpenFeatureClass("Parcels");
			
			// Open the Shapefile workspace and the Owners DBF file.
			Type shpFactoryType = Type.GetTypeFromProgID("esriDataSourcesFile.ShapefileWorkspaceFactory");
			IWorkspaceFactory shpWorkspaceFactory = (IWorkspaceFactory)Activator.CreateInstance(shpFactoryType);
			IWorkspace shpWorkspace = shpWorkspaceFactory.OpenFromFile(@"..\..\..\Data", 0);
			IFeatureWorkspace shpFeatureWorkspace = (IFeatureWorkspace)shpWorkspace;
			IObjectClass objectClass = (IObjectClass)shpFeatureWorkspace.OpenTable("Owners");

			// Create a memory relationship class between the two datasets.
			IMemoryRelationshipClassFactory memRelClassFactory = new MemoryRelationshipClassFactoryClass();
			IRelationshipClass relationshipClass = memRelClassFactory.Open("ParcelsOwners",
				featureClass, "PROPERTY_I", objectClass, "PROPERTY_I", "Is Owned By", "Owns",
				esriRelCardinality.esriRelCardinalityOneToOne);

			// Create a RelQueryTable using the memory relationship class.
			IRelQueryTableFactory relQueryTableFactory = new RelQueryTableFactoryClass();
			ITable relQueryTable = (ITable)relQueryTableFactory.Open(relationshipClass,
				true, null, null, "", true, false);

			// Create a query filter that finds the names of the owners of large parcels.
			IQueryFilter queryFilter = new QueryFilterClass
			{
				SubFields = "Parcels.PROPERTY_I, Owners.OWNER_NAME",
				WhereClause = "Parcels.SHAPE_AREA > 300000"
			};

			// Find the indexes of the Property ID and Owner Name fields.
			int propertyIdIndex = relQueryTable.FindField("Parcels.PROPERTY_I");
			int ownerNameIndex = relQueryTable.FindField("Owners.OWNER_NAME");

			// Execute a query, displaying the names of the owners.
			using (ComReleaser comReleaser = new ComReleaser())
			{
				ICursor cursor = relQueryTable.Search(queryFilter, true);
				comReleaser.ManageLifetime(cursor);

				IRow row = null;
				while ((row = cursor.NextRow()) != null)
				{
					Console.WriteLine("Owner of Property {0} is: {1}", row.get_Value(propertyIdIndex),
						row.get_Value(ownerNameIndex));
				}
			}

			// Shutdown the licensing.
			aoInitialize.Shutdown();
		}
	}
}

注意：其实也可以使用sdetable -o create_view来创建关联视图，这样的话，用户可以操作视图（跟普通要素类一样）来进行查询，但是视图是只读对象，不能编辑。

另外还可以使用IQueryDef接口来进行关联

public void IQueryDef_Example(IWorkspace workspace)

    { 
        IFeatureWorkspace featureWorkspace = (IFeatureWorkspace)workspace; 
        //create query definition 
        IQueryDef queryDef = featureWorkspace.CreateQueryDef(); 
        //provide list of tables to join 
        queryDef.Tables = "datesjoin,dudatest"; 
        //retrieve the fields from all tables 
        queryDef.SubFields = "sde.datesjoin.dt_field = sde.dudates.dt_field"; 
        //set up join 
        queryDef.WhereClause = "datesjoin.dt_field = dudates.dt_field";

        //Create FeatureDataset. Note the use of .OpenFeatureQuery. 
        //The name "MyJoin" is the name of the restult of the query def and 
        //is used in place of a feature class name. 
        IFeatureDataset featureDataset = featureWorkspace.OpenFeatureQuery("MyJoin", queryDef); 
        //open layer to test against 
        IFeatureClassContainer featureClassContainer = (IFeatureClassContainer)featureDataset; 
        IFeatureClass featureClass = featureClassContainer.get_ClassByName("MyJoin");

    }

源代码以及数据下载