heitml supports the MySQL database system. MySQL is very fast and free in some cases. MySQL however does not support transactions and no rollback. This makes MySQL fine for applications that query a database or perform at most one update statement per page access.

WARNING: If a page performs multiple updates it can happen, that in case of an error condition some but not all updates are performed. Application programs must take this into account otherwise an error condition leads to an inconsistent database. Note that it is not possible to avoid all possible error conditions, like network failures, users pressing the stop button of the browser, a wrong and crashing heitml application program, an unclean shut down of the Web server, or a hardware or operating system failure.

On RedHat and Debian Linux there is a .rpm or .deb file for heitml available. It drastically minimizes installation overhead. These files work with the MySQL versions that are on the Linux distribution CDs. For RedHat we used MySQL version 3.22.26.

Furthermore, there is the generic version of heitml that comes as a precompiled module and contains the database drivers as source code. You need to link in the MySQL library. This probably works with any MySQL version.

• heitmluser, heitmlpasswd are not required for MySQL, but they can be given to overwrite the MySQL defaults
• heitmldbname must give the database name
• heitmldbhost must give the hostname where the database server is running (if it runs on a remote machine)