>Hi All,
I'm looking at using PHP and MySQL for a particular website application.
However, I was a bit concerned that if a PHP script went wrong then it would
be possible to accidentally delete or overwrite large chunks of the data in
the database which presumably would then be lost. What is the usual
procedure for these situations?. Is it possible to back up a database
somehow so that data from a previous time can be retrieved?.
mysqldump.
If you can access your MySQL database directly from a host you
control (e.g. your desktop), dump it to a file on your desktop.
You do need to install the MySQL client on that machine.
This option may not be available as hosts don't allow it or
you don't want your db accessable remotely.
If you can access your MySQL database from a shell account on
the hosting server, dump it to a file on the hosting server,
then FTP it somewhere else safe (if the hosting server loses
a hard drive, it might lose the master copy AND your backup
if you don't keep a copy elsewhere).
If you have to use PHP to access MySQL, invoke mysqldump from PHP
(exec()) and redirect the output to a file on the hosting server,
then FTP it somewhere else safe.
You restore stuff generated by mysqldump (which is a series of SQL
commands) by feeding the dump into the command line client called 'mysql',
e.g. for UNIX shells:
mysqldump -h host -u user -ppassword --databases db1 db2 ... > mysql.dump
mysql -h host -u user -ppassword db1 < mysql.dump
mysqldump has lots of options. Depending on your hosting situation,
you may want to back up all databases or just the one your host
assigns to you. Or maybe you want just specific tables. You can
back up just the schema (no data) or all of it. Some of the options
(like host name) may default properly in the right circumstances.
Gordon L. Burditt
