C# Arcengine 设置默认数据库

IWorkspaceName name = new WorkspaceNameClass();
name.WorkspaceFactoryProgID = "esriDataSourcesGDB.FileGDBWorkspaceFactory";
name.PathName = @"E:\Projects\WorldSoil\ProjectData.gdb";
IGxCatalogDefaultDatabase gdb = app as IGxCatalogDefaultDatabase;
gdb.DefaultDatabaseName = name;