Oracle 5.0 Reference Manual page 2331

The mysqli extension features a dual interface. It supports the procedural and object-oriented
programming paradigm.
Users migrating from the old mysql extension may prefer the procedural interface. The procedural
interface is similar to that of the old mysql extension. In many cases, the function names differ only
by prefix. Some mysqli functions take a connection handle as their first argument, whereas matching
functions in the old mysql interface take it as an optional last argument.
Example 20.77. Easy migration from the old mysql extension
<?php
$mysqli = mysqli_connect("example.com", "user", "password", "database");
$res = mysqli_query($mysqli, "SELECT 'Please, do not use ' AS _msg FROM DUAL");
$row = mysqli_fetch_assoc($res);
echo $row['_msg'];
$mysql = mysql_connect("localhost", "root", "");
mysql_select_db("test");
$res = mysql_query("SELECT 'the mysql extension for new developments.' AS _msg FROM DUAL", $mysql);
$row = mysql_fetch_assoc($res);
echo $row['_msg'];
?>
The above example will output:
Please, do not use the mysql extension for new developments.
The object-oriented interface
In addition to the classical procedural interface, users can choose to use the object-oriented interface.
The documentation is organized using the object-oriented interface. The object-oriented interface
shows functions grouped by their purpose, making it easier to get started. The reference section gives
examples for both syntax variants.
There are no significant performance differences between the two interfaces. Users can base their
choice on personal preference.
Example 20.78. Object-oriented and procedural interface
<?php
$mysqli = mysqli_connect("example.com", "user", "password", "database");
if (mysqli_connect_errno($mysqli)) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$res = mysqli_query($mysqli, "SELECT 'A world full of ' AS _msg FROM DUAL");
$row = mysqli_fetch_assoc($res);
echo $row['_msg'];
$mysqli = new mysqli("example.com", "user", "password", "database");
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: " . $mysqli->connect_error;
}
$res = $mysqli->query("SELECT 'choices to please everybody.' AS _msg FROM DUAL");
$row = $res->fetch_assoc();
echo $row['_msg'];
?>
The above example will output:
MySQL Improved Extension (Mysqli)
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