To insert a new table into a database diagram
A new table appears in the diagram in Column Properties view.
Press the TAB key to move to the next cell.
Each column must have a name and data type. You can set other properties for the column by typing or selecting values, or you can accept the default settings.
When you save your database diagram, the new table will be added to your database.
Note If you create a new table, then remove it from the diagram before saving it to the database, the table name remains in memory until you close the database diagram. Also, if you delete an existing table from the database, the table name remains in memory. To use the table name again, close and reopen the database diagrams.
Adding Tables to a Database Diagram | How to open a database diagram |