MySQL Gotchas

This site contains a very detailed list of gotcha's with MySQL (i.e. unusual behaviour not consistent with the majority of other databases out there). They are not necessarily bugs. It's quite hard core and very detailed, but could be useful if you're ever scratching your head wondering why something odd is going on with your MySQL queries.
 
Topics include

• Strange null behaviour
• Varchar fields are non-case sensitive by default
• Peculiar comment behaviour
• Division by zero gives null rather than an error

and dozens more