I think the MySQL Documentation has a little bit on Database Design which is mainly used for MySQL, however any RDMS (Relation Database Management System) will work similarly like the SQL Statement I used then you could use with little to no modification in PostgreSQL for example however I have never used PostgreSQL.
There is however a Book I was told to get during this year on MySQL, which was used during the Database Design class I did forgot what the book was called now however it went fairly in depth into Database Design with MySQL. Most tutorials will only scratch the surface of a particular Database. SitePoint.com Articles has a fairly good one I believe.