As someone has pointed out on the Opera-Users mail list, from the license of Opera 9.21 for Macintosh:

“You may not use the Software on non-PC products, devices, or embedded in any other product…”

So are all Mac users infringing the license? ;)

One of MySQL’s restriction when using views is that they cannot refer to local variables. So, for example, this statement will produce an error:

create view thematical_books as
select title
     , author
  from books
 where subject = @book_subject

A workaround for this limitation is quite simple: to use a function which returns variable value. For example:

create function book_subject()
returns varchar(64) as
return @book_subject;

create view thematical_books as
select title
     , author
  from books
 where subject = book_subject()