Is there any difference between the ways php connects to mysql?

Difference: 1. PDO is used in 12 different databases, while MySQLi is only used in the mysql database; 2. The way PDO closes the connection is "$conn = null", while the way MySQLi closes the connection is "$conn->close()" or "mysqli_close()".

The operating environment of this article: Windows 10 system, PHP version 7.1, Dell G3 computer.

Is there any difference between the ways in which php connects to mysql?

After php5.3 version, there are two ways to connect to the database, one is through mysqli, and the other is Connecting to the database through PDO and through mysqli can also be divided into two situations: mysqli (object-oriented), mysqli (process-oriented).
There are three ways:
1) PDO connects to mysql
2 ) mysqli (object-oriented) connects to the database
3) mysqli (process-oriented) connects to the database
(In fact, there is another connection method: using the MySQL extension. However, this extension is not recommended for use in 2012.)

PDO connection example

You can first check whether your php has PDO installed through the phpinfo() command (I use php7, it is already installed by default)
If it is not installed, refer to the web page: http://php.net/manual/en/pdo.installation.php

Code example:

<?php $servername = "localhost";
$username = "root";
$password = "root";
try {
    $conn = new PDO("mysql:host=$servername;dbname=jtsys",
        $username, $password);
    echo "连接成功";
}
catch(PDOException $e)
{
    
    echo $e->getMessage();
}
?>

(Please pay attention to changes when using Database user name and password, as well as the selected database name (dbname)

mysqli (object-oriented) connection instance

You can first check yours through the phpinfo() command Whether mysqli has been installed in php (I use php7, it is already installed by default)
If not, please refer to the web page: http://php.net/manual/en/mysqli.installation.php

Code example:

<?php $servername = "localhost";
$username = "root";
$password = "root";
// 创建连接
$conn =
new mysqli($servername, $username, $password);
// 检测连接
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}
$dbname="jtsys";
mysqli_select_db($conn,$dbname);
echo "连接成功";
?>

mysqli (process-oriented) connecting to the database

Code example:

<?php $servername = "localhost";
$username = "root";
$password = "root";
// 创建连接
$conn = mysqli_connect($servername, 
$username, $password);
// 检测连接
if (!$conn) {
    die("Connection 
failed: " . mysqli_connect_error());
}
$dbname="jtsys";
mysqli_select_db($conn,$dbname);
echo "连接成功";
?>

The difference between the three :

1. How to close the connection:
PDO:

$conn = null;

MySQLi (object-oriented):

$conn->close();

MySQLi ( Process-oriented):

mysqli_close($conn);

• PDO is applied in 12 different databases, MySQLi is only for MySQL database.
• If your project needs to switch between multiple databases, it is recommended to use PDO , so you only need to modify the connection string and department query statement. Using MySQLi, if it is a different database, you need to rewrite all code, including queries.
• Both are object-oriented, but MySQLi also provides API interface.
• Both support prepared statements. Prepared statements can prevent SQL injection and are very important for the security of web projects.
  MySQLi The difference between object-oriented and process-oriented:
  Many PHP programmers are not used to object-oriented programming, so the mysqli class library provides this method for them to use. This is also convenient for some users who use the mysql extension to quickly migrate to mysqli. In fact, mysqli_query() is an encapsulation of the object-oriented calling process.

Recommended learning: "PHP Video Tutorial"

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