About Database Diagrams Affected by Another UserÆs Changes

In a multiuser environment, your database diagram can be affected by changes other users have saved to:

• Your database diagram, which other users changed since you opened the diagram.
• Database objects shared between database diagrams.
• The database.

For example, your database diagram might contain a table that another user deleted or renamed. In such a case, your database diagram will no longer reflect the current state of the database. When you attempt to save your database diagram or selected tables, the Database Changes Detected dialog box notifies you that the database has been updated since you opened your diagram.

This dialog box also displays a list of database objects that will be affected as a result of saving your database diagram or selection. At this point, you can take one of these actions:

• Save your database diagram or selection and update the database with all the changes in the list.   This action will also affect other database diagrams that share the same database objects.
  For example, suppose you edit the au_id column in the titleauthors table on your database diagram and another userÆs database diagram contains the authors table which is related to the titleauthors table by the au_id column. Saving your database diagram will affect the other userÆs database diagram. Similarly, suppose that another user defined a check constraint for the qty column in the sales table. If you delete the qty column and save the sales table, the other userÆs check constraint will be affected.
• Cancel the save action.   You can then close the database diagram without saving it. When you reopen the database diagram, it will be in synch with the database.
• Save a list of the changes.   You can save the list of database changes shown in the Database Changes Detected dialog box to a text file so that you can investigate the cause of other usersÆ changes.
  For example, if another user edited a table that you marked for deletion, you may want to research whether the table should be deleted before updating the database.