Several ways to connect to the database in php

For PHP 5 and above, it is recommended to use the following method to connect to MySQL:

MySQLi: MySQLi only targets MySQL database, and MySQLi also provides an API interface. . PDO (PHP Data Objects): PDO is used in 12 different databases.

Common points:

1. Both are object-oriented

2. Both support prepared statements. Prepared statements can prevent SQL injection and are very important for the security of web projects.

Make sure that MySQLi or PDO has been installed in wamp, view method: echo phpinfo();

The following three methods will be used to demonstrate PHP operations. MySQL:

1., MySQLi - object-oriented

<?php
header(&#39;Content-Type: text/html;charset=utf-8&#39;);

//echo phpinfo();

// MySQLi面向对象
// 在我们访问MySQL数据库之前，我们需要先连接到数据库服务器
$servername = "localhost";
$username = "root";
$password = "";

// 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);
}

echo "连接成功";
?>

2, MySQLi - process-oriented

<?php
header(&#39;Content-Type: text/html; charset=utf-8&#39;);

// MySQLi - 面向过程
$servername = "localhost";
$username = "root";
$password = "";

// 创建连接
$conn = mysqli_connect($servername, $username, $password);

// 检测连接
if(!$conn)
{
    die("连接失败：" . mysqli_connect_error());
}

echo "连接成功";
?>

3. PDO connects to MySQL database

PDO needs to set the database name. If it is not specified, an exception will be thrown

<?php
header(&#39;Content-Type: text/html; charset=utf-8&#39;);

// PDO连接MySQL数据库
// PDO要设置数据库名，如果没有指定，则会抛出异常

$servername = "localhost";
$username = "root";
$password = "";
$dbname = "mugua";

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

The connection will be automatically made after the script is executed. Close, you can also use code to close the connection:

1, MySQLi - Object-oriented

$conn->close() ;

2, MySQLi - process-oriented

mysqli_close($conn);

3, PDO

$conn = null;

Recommended tutorial: PHP video tutorial

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