I have recently blogged about 10 common mistakes Java developers make when writing SQL. These mistakes apply to all other developers (including SQL developers) as well, of course:
http://blog.jooq.org/2013/07/30/10-common-mistakes-java-developers-make-when-writing-sql/[/url]
http://blog.jooq.org/2013/08/12/10-more-common-mistakes-java-developers-make-when-writing-sql/[/url]