Uploading data from the FCKEditor to a MySQL database causes an update error, but only when editing an existing database record. Is there a problem with either the PHP script or database?

First check that the script you are running correctly updates the database, when using a plain text input or textarea form field. If the update is successfully then check the php.ini configuration file on your server.

If "magic_quotes_gpc = Off " then change it to "magic_quotes_gpc = On" this should rectify the error.

Note it is not a good idea to run with magic quotes On unless absolutely necessary. Look at updating the PHP script used to eliminate the need for magic quotes and then switch them back off if possible.