MySQL vs MySQLi when using PHP

If you have a look at MySQL Improved Extension Overview, it should tell you everything you need to know about the differences between the two.

The main useful features are:

• an Object-oriented interface
• support for prepared statements
• support for multiple statements
• support for transactions
• enhanced debugging capabilities
• embedded server support.

There is a manual page dedicated to help choosing between mysql, mysqli and PDO at

• http://php.net/manual/en/mysqlinfo.api.choosing.php and
• http://www.php.net/manual/en/mysqlinfo.library.choosing.php

The PHP team recommends mysqli or PDO_MySQL for new development:

It is recommended to use either the mysqli or PDO_MySQL extensions. It is not recommended to use the old mysql extension for new development. A detailed feature comparison matrix is provided below. The overall performance of all three extensions is considered to be about the same. Although the performance of the extension contributes only a fraction of the total run time of a PHP web request. Often, the impact is as low as 0.1%.

The page also has a feature matrix comparing the extension APIs. The main differences between mysqli and mysql API are as follows:

                               mysqli     mysql
Development Status             Active     Maintenance only
Lifecycle                      Active     Long Term Deprecation Announced*
Recommended                    Yes        No
OOP API                        Yes        No
Asynchronous Queries           Yes        No
Server-Side Prep. Statements   Yes        No
Stored Procedures              Yes        No
Multiple Statements            Yes        No
Transactions                   Yes        No
MySQL 5.1+ functionality       Yes        No

_{* http://news.php.net/php.internals/53799}

There is an additional feature matrix comparing the libraries (new mysqlnd versus libmysql) at

• http://www.php.net/manual/en/mysqlinfo.library.choosing.php

and a very thorough blog article at

• http://blog.ulf-wendel.de/2012/php-mysql-why-to-upgrade-extmysql/

I have abandoned using mysqli. It is simply too unstable. I've had queries that crash PHP using mysqli but work just fine with the mysql package. Also mysqli crashes on LONGTEXT columns. This bug has been raised in various forms since at least 2005 and remains broken. I'd honestly like to use prepared statements but mysqli just isn't reliable enough (and noone seems to bother fixing it). If you really want prepared statements go with PDO.

MySQLi stands for MySQL improved. It's an object-oriented interface to the MySQL bindings which makes things easier to use. It also offers support for prepared statements (which are very useful). If you're on PHP 5 use MySQLi.