大部分的集合和容器对象都是通过 Document 或 Database 对象访问的。Document 和 Database 对象都包含一些相应的特性用来访问大多数可用集合的对象或对象 ID。例如，以下代码定义一个变量，并将其设置为当前图形的 LayersTable 对象：
'' 获得当前图形并启动一个事务管理器 Get the current document and start the Transaction Manager
Dim acCurDb As Database = Application.DocumentManager.MdiActiveDocument.Database
Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()
'' 这个例子返回当前数据库的层表 This example returns the layer table for the current database
Dim acLyrTbl As LayerTable
acLyrTbl = acTrans.GetObject(acCurDb.LayerTableId, _
OpenMode.ForRead)
''事务销毁 Dispose of the transaction
End Using
// Get the current document and start the Transaction Manager
Database acCurDb = Application.DocumentManager.MdiActiveDocument.Database;
using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
{// This example returns the layer table for the current database
LayerTable acLyrTbl;
acLyrTbl = acTrans.GetObject(acCurDb.LayerTableId,
OpenMode.ForRead) as LayerTable;
// Dispose of the transaction
}
