why not to use mysql   (link)

http://sql-info.de/mysql/gotchas.html
It's not a bug - it's a gotcha. A "gotcha" is a feature or function which works as advertised - but not as expected.

When working with the MySQL ™ database server I have repeatedly encountered situations where the results of various actions have been unexpected and/or contrary to the behaviour generally expected of an SQL relational database. The cause can usually be traced to implementation details which are documented in the manual. I have created this list in order to further a better understanding of the MySQL database server and hopefully save others unnecessary headscratching.