Problem "one database - many sites" solved when use prefix in table names.
Drupal (and other CMS) provides settings to specify the database table prefix during the installation. This prefix after the installation set in /sites/default/settings.php - and if you are going to add or change the table names prefix, you need to correct file settings.php.
(The text is translated by Google Translate and corrected by tlito.)
How do people can copy content from any good site if there is no right click menu or impossible to select text? If you do not want to violate the laws and regulations of the sites from which you just want to copy the text, you can use then the following advice. If you want to blatantly steal content, you don't need to use the next tip.
To disallow copying can be used, for example, a script like this: