How to: Upgrade Database Diagrams from Previous Editions (Visual Database Tools)
Database diagrams created on previous editions of SQL Server databases are upgraded automatically when database diagramming is set up on Microsoft SQL Server 2005. For more steps for setting up diagramming see How to: Set Up Database Diagram Designer (Visual Database Tools).
To upgrade legacy database diagrams
From Object Explorer, expand the database.
Expand the Database Diagram node under the database.
Select Yes when prompted if you want to set up database diagramming.
This will upgrade diagrams stored on the database.
See Also
Tasks
How to: Set Up Database Diagram Designer (Visual Database Tools)
Concepts
Understanding Database Diagram Ownership (Visual Database Tools)