Migrating from MySQL to MySQLi: A Comprehensive Guide

When migrating your site from MySQL to MySQLi, the primary focus lies on modifying your PHP code. The database itself remains largely unaffected.

PHP Code Substitution

Yes, you can directly replace MySQL functions with their MySQLi counterparts. However, each function in MySQLi takes an additional parameter: the established MySQLi connection. For example, the following MySQL query:

$result = mysql_query("SELECT * FROM users");

Becomes:

$connection = new mysqli(MYSQLI_HOST, MYSQLI_USER, MYSQLI_PASSWORD, MYSQLI_DB);
$result = $connection->query("SELECT * FROM users");

Note: Obsolete MySQL functions such as mysql_connect() and mysql_select_db() are not available in MySQLi.

Additional Considerations

• Error Handling: MySQLi uses a different approach for error handling. Learn the new syntax for reporting and handling errors.
• Connection Management: MySQLi introduces the concept of persistent connections. Review documentation on managing connections efficiently.
• Legacy Code Support: If your site contains legacy code that uses MySQL functions, consider creating a transition layer to support both MySQL and MySQLi.
• Database Toolkit: Some database toolkits (e.g., Active Record) may support MySQLi automatically. Check the documentation for your particular toolkit.

Reference Material

Consult the following resources for more detailed information:

• [Converting to MySQLi](https://www.php.net/manual/en/mysqli.intro-mysqli.php)
• [Comparison of MySQL and MySQLi Function Parameters](https://www.php.net/manual/en/function.mysql-query.php#97106)