There are two major problems with this class: 1) you use $_S...

There are two major problems with this class:

1) you use $_SESSION for storing and retrieving SQL data, so when you want to clean your cache, you clear entire user session (see session_destroy()) - this is a major problem for most of the homebrew PHP scripts which, and even some advanced (which use custom session handlers and database storage)

2) there is a potential problem with mysql_real_escape, you really should use connection handler in all of your mysql_* functions, because some scripts will be using two or more different MySQL connections (for example with different encodings).

thank u , i will fix this, it was very basic example, so i don't think about complex projects..