PHP 连接 MySQL

连接 MySQL
在我们访问 MySQL 数据库前，我们需要先连接到数据库服务器：

面向对象

<?php
$servername = "localhost";
$username = "username";
$password = "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";
?>

面向过程

<?php
$servername = "localhost";
$username = "username";
$password = "password";

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

// 检测连接
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
echo "连接成功";
?>

关闭连接

连接在脚本执行完后会自动关闭。你也可以使用以下代码来关闭连接：
实例 (MySQLi - 面向对象)

$conn->close(); 

实例 (MySQLi - 面向过程)

mysqli_close($conn); 

创建数据库

实例 (MySQLi - 面向对象)

<?php
$servername = "localhost";
$username = "username";
$password = "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);
} 

// 创建数据库
$sql = "CREATE DATABASE myDB";
if ($conn->query($sql) === TRUE) {
    echo "数据库创建成功";
} else {
    echo "Error creating database: " . $conn->error;
}

$conn->close();
?>

实例 (MySQLi Procedural)

<?php
$servername = "localhost";
$username = "username";
$password = "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());
}

// 创建数据库
$sql = "CREATE DATABASE myDB";
if (mysqli_query($conn, $sql)) {
    echo "数据库创建成功";
} else {
    echo "Error creating database: " . mysqli_error($conn);
}

mysqli_close($conn);
?>

创建 MySQL 表（实例 (MySQLi - 面向对象)）

<?php
$servername = "localhost";
$username = "username";
$password = "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());
}

// 创建数据库
$sql = "CREATE DATABASE myDB";
if (mysqli_query($conn, $sql)) {
    echo "数据库创建成功";
} else {
    echo "Error creating database: " . mysqli_error($conn);
}

mysqli_close($conn);
?>

实例 (MySQLi - 面向过程)

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// 创建连接
$conn = mysqli_connect($servername, $username, $password, $dbname);
// 检测连接
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}

// 使用 sql 创建数据表
$sql = "CREATE TABLE MyGuests (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY, 
firstname VARCHAR(30) NOT NULL,
lastname VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP
)";

if (mysqli_query($conn, $sql)) {
    echo "数据表 MyGuests 创建成功";
} else {
    echo "创建数据表错误: " . mysqli_error($conn);
}

mysqli_close($conn);
?> 

其他的就跟Mysql语法一样很简单，具体语法可以参考一下后面笔记的Mysql语法篇