Entity Relationship Diagram - Get Now DOC

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					Entity Relationship Diagram

Draw an Entity Relationship Diagram using the Visio program. These instructions are for the
"crows feet" style of ERDs using Visio 2003. There are many other styles and Visio 2007
probably has a ribbon instead of menus and toolbars.

   1. Open Visio and create a new file with File > New > New Drawing.
   2. In the Search for Shapes combo box, type "Database"
   3. A dialog will appear that the search results are greater than 100. Select Yes to see
       the results.
   4. Change the zoom from the default of 50% to 100% or some other size to your liking.
   5. Find the Entity1 shape (square) and drag one copy onto the grid sheet for every entity
       in your database. Position them about 1.5 - 2 inches apart.
   6. Save the diagram using the usual naming convention. The key word for the diagram
       should be the name of the database problem. Resave every 10-15 minutes.
   7. Double click in each square and type the name of the entity.
   8. Find the Entity Relationship shape (diamond). Drag a shape for each relationship verb
       and position roughly midway between the entity shapes.
   9. Double click in each diamond and type the relationship verb that describes how each
       pair of relationships are related to each other.
   10. Turn on the display of connection points View > Connection Points. The connection
       points appear as blue letter "x"s.
   11. Find the Drawing tools by right clicking in the toolbar and selecting Drawing from the
       popup menu, or by clicking on the Drowing tools button in the Toolbar.
   12. Select the Line Tool. Move the mouse pointer to the connection point of one entity to
       the connection point of the entity to which it is related. When the mouse hovers over
       the connection points a small red rectangle will appear. The line will appear on top of
       the diamond (see next step).
   13. Repeat for each connection line between entities.
   14. Close the Drawing Tools Toolbar. This is essential for the following steps to be
       carried out.
   15. Right click anywhere on the line and select Shape from the popup menu. Select "Send
       to Back" and the line will move behind the diamond.
   16. Next format the ends of the line. Right click on the line and select Format, and then
       Line.
   17. Change the Line Ends: Begin: 24 (vertical line signifies the parent entity). End: 27
       ("crows feet" signifies the child entity). Be sure to click on OK (or Apply to preview;
       and then OK) before closing the Format dialog.
   18. Either repeat steps 11-17; or copy, paste and edit the line(s) between other pairs of
       entities.
   19. Save the file and close Visio.
1. Create a new drawing




2. Search for database shapes.




3. More than 100 shapes. Click on Yes.




4. Find the entity and entity relationship shapes. Note that scroll bar is about 1/2 way down.
   Note: use the Entity 1 shape as the Entity shape allows for the creation of fields in the ERD and creation
of the DB from the ERD.
5. The Drawing Toolbar for drawing the line between entities.




6. Line format dialog with end settings
This is the demo ERD drawn on the board.The assignment was identical except for the entity names and
relationship verbs. The verbal expression of the relationships were hand written in class by students from a
lecture.

A business rule limits a theft to a single bicycle to avoid M:N relationships for this :neighborhood watch”
database.

				
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posted:7/27/2012
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