A: Use the CopySelection and PasteSelection methods to copy the selected items to a second Diagram instance, and call the Diagram.SaveToFile method to save them to a file.
A: No. You should read the schema by ADO.NET and generate a diagram programmatically with the CreateTableNode and CreateDiagramLink methods.
Q: I have an SQL-Table with some entries containing state and connection information in several columns. I already imported the nodes. Now I would like to organize the connections. Have you some hints which way I should choose to reach that?
A: To create the connections, assign the node ID from the database to the ShapeNode.Tag property while creating the nodes. Run a second loop over the link records, and for each related node ID you have for a node, call CreateDiagramLink(node, Diagram.FindNode (relatedID)). If you already use the Tags to store other information, save the relations in a Hashtable. To arrange the diagram, use some of the layout algorithm classes, for example LayeredLayout.