The difference and usage of MySQL and mysqli

The difference and usage of MySQL and mysqli

MySQL is a non-holding relay function and MYSQLI is a permanent connection function. Other words

MySQL each link will open a connected process and mysqli run mysqli multiple times will use the same connection process, thereby reducing the cost of the server

Some friends use the new mysqli (' localhost ', usenamer ', ' Password ', ' DatabaseName ') when programming, and always error, Fatal error:class ' mysqli ' not found In D: ...

is the Mysqli class not PHP-led?

Not the default to open, win under to change php.ini, remove Php_mysqli.dll before;, Linux to the mysqli compiled into