how can i find out if my database design (specially relationships) are ok? i found some database examples on the internet and tried to solve them but my design is always different than the examples design. is there a any rules to follow when designing relationships or any questions to ask myself to find out if my relations are bad? or is it possible for a database to have more than one OK design? thanks
Everyone has his/her own styles in database design. What you see on the internet are also good but that is their own interpretation of the business rules given to them. You would know if your database design is okay if there is no redundancy in your data or maybe lesser than it should have been. Efficient and would be easy to call using your queries. but if you want to know what the common mistakes in designing are, then here is a link for you
http://www.simple-talk.com/sql/database-administration/ten-common-database-design-mistakes/