Lex de Haan (11 August 1954 – 1 February 2006) was an independent author, lecturer, researcher, and consultant, specializing in relational database technology. == Biography == Lex was a teacher of Mathematics/Informatics in secondary school level during the years between 1976 and 1985. Between 1985 and 1989 Lex was employed for one year in the research department of a Dutch independent system vendor - Minihouse/Multihouse - and then moved to the education department, where he developed and delivered courses in the following areas: relational databases and SQL, Oracle system development, and database administration (Oracle versions 4/5/6), Unix for system users and Unix system administration, VAX/VMS for system users and VAX/VMS system administration, and teaching...