Object data is an efficient method for storing small amounts of attribute data that you want to associate with drawing objects, but external databases store larger amounts of data more efficiently, and allow for more complex queries.
With AutoCAD Map 3D, you can convert object data into a linked database table that has the same data structure as the object data table. For each object containing object data in the specified table, AutoCAD Map 3D does the following:
When AutoCAD Map 3D converts the data, it creates a new table in an existing data source. It also creates a link template for the new table. In the link template, you can choose to use an existing field as the key field, or you can have AutoCAD Map 3D create a new field and assign a unique value to each record.