1.

IWorkspaceFactory2 workspaceFactory = new ShapefileWorkspaceFactoryClass() as IWorkspaceFactory2;            IWorkspace workspace = workspaceFactory.OpenFromFile(@"E:\", 0);            IFeatureWorkspace featureWorkspace = (IFeatureWorkspace)workspace;            IFeatureClass featureClass = featureWorkspace.OpenFeatureClass(“a”);            IFeatureClass featureClass2 = featureWorkspace.OpenFeatureClass( "b");             AddJoin aj = new AddJoin();            aj.in_field = "ID";            aj.in_layer_or_view = featureClass2; // @"E:\jhl\" + Functions.g_ROAD + "_SpatialJoin";            aj.join_field = "FID";            aj.join_table = @"E:\a.shp";            //aj.out_layer_or_view = Functions.g_ROAD + "_SpatialJoin";            aj.join_type = "KEEP_ALL";            Geoprocessor gp = new Geoprocessor();            //gp.OverwriteOutput = true;            gp.Execute(aj, null);

 

 

2.

//// Build a memory relationship class.            Type memRelClassFactoryType =Type.GetTypeFromProgID("esriGeodatabase.MemoryRelationshipClassFactory");            IMemoryRelationshipClassFactory memRelClassFactory = (IMemoryRelationshipClassFactory)Activator.CreateInstance(memRelClassFactoryType);            IRelationshipClass relationshipClass = memRelClassFactory.Open("a", featureClass2, "ID", (IObjectClass)featureClass,                "FID", "Is Owned By", "Owns",esriRelCardinality.esriRelCardinalityOneToOne);            // Open the RelQueryTable as a feature class.            Type rqtFactoryType =Type.GetTypeFromProgID("esriGeodatabase.RelQueryTableFactory");            IRelQueryTableFactory rqtFactory = (IRelQueryTableFactory)Activator.CreateInstance(rqtFactoryType);            ITable relQueryTable = (ITable)rqtFactory.Open(relationshipClass, false, null,null, string.Empty, false, false);

 

 

3.

            

// Create the query definition.            IQueryDef queryDef = featureWorkspace.CreateQueryDef();            // Provide a list of tables to join.            queryDef.Tables = "a,b";            queryDef.Tables += "";            // Set the subfields and the WhereClause (in this case, the join condition).            queryDef.SubFields = "*";            queryDef.WhereClause = "a.ID = b.FID + 1";             // Make the new TableQueryName.            IQueryName2 queryName2 = (IQueryName2)new TableQueryNameClass();            queryName2.QueryDef = queryDef;            queryName2.PrimaryKey = "ID";            queryName2.CopyLocally = true;             IDataset workspaceDataset = (IDataset)featureWorkspace;            IWorkspaceName workspaceName = (IWorkspaceName)workspaceDataset.FullName;             // Set the workspace and name of the new QueryTable.            IDatasetName datasetName = (IDatasetName)queryName2;            datasetName.WorkspaceName = workspaceName;            datasetName.Name = "Join";             // Open the virtual table.            IName name = (IName)queryName2;            ITable table = (ITable)name.Open();