Ten Common Database Design Mistakes

the list:

1. Poor design/planning
2. Ignoring normalization
3. Poor naming standards
4. Lack of documentation
5. One table to hold all domain values
6. Using identity/guid columns as your only key
7. Not using SQL facilities to protect data integrity
8. Not using stored procedures to access data
9. Trying to build generic objects

10. Lack of testing

http://www.simple-talk.com/sql/database-administration/ten-common-database-design-mistakes/