one easy alternative is using GROUP_CONCAT() comparing the result with whatever string you like.http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat
oh...I forget to say...I do not know what is exactly PID is.
They are assigned by the system (for each book), and there are holes between them, i.e.
3, 4, 6, 11, 12, ...., 667, 668, 671,...
I mean, I know at best their range, i.e. starting from 1 to some large number.
I know they are integer, countable, and positive
The problem is my database is somewhat inconsistent now.
Every book (PID) should have three (1,2,3) languages. But apparently some are missing.
I need to find out which one is missing.