I have two programmers coming into my group. One is a mainframe programmer (cobol, cics, DB2), the other is a DOS batch and Perl programmer.

They need to learn PL/SQL and I need a book/reference material that they can use and learn on their own.

Does anyone have any suggestions (preferable a good PL/SQL book for beginners)?

They will be attending Oracle 9i classes (first quarter 2002).