A MySQL many to many relationship is a relationship that is multi-valued in both directions. Given that, how can you select rows that don’t have a specific relationship (the exclude relation problem)? I will start by defining the MySQL Many to Many relationship (Experts can skip to the next paragraph) What is A MySQL many [...]

I gave two presentations about Gearman at the Linux.conf.au. As part of the preparation for these talks, I created several sample applications. One of them, about remote replication administration, I will cover in a separate post. The most amazing one, which I cover here, is a quick and painless solution for multiple level crosstabs in MySQL.

Some background is needed. Crosstabs (also called data cubes or pivot tables, have been one of my favorite hacks for long time. In 2001 I wrote an article about a simple




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