Sql-related IdiomOrPattern can help those of us who are using relational database for more than a persistent storage for objects. They are applicable only in StructuredQueryLanguage, which is, however, the only relational language around, so they can be considered patterns.
Some patterns are:
See also SqlMyopia - hopefully patterns help to cure it ;)
Table-Oriented GOF-like patterns: http://geocities.com/tablizer/prpats.htm
See Also: SqlFlaws, DatabaseBestPractices