database design

1. Describe at least two examples of common errors in entity relationship modeling. If possible, provide a graphical illustration of the problems and solutions. List some questions the designer should consider before designing the models so that these errors can be avoided. 

2. Using library resources or the Internet, locate an entity relationship diagram (ERD) utility that can be used to create graphic database designs. Provide a general description about the company that produces the tool. Mention the ER modeling techniques offered by the tool and the database products that it supports. Discuss other features that might make this an attractive product to a database designer and explain why.