PHP怎么连接MySQL数据库并获取数据

使用mysqli或PDO扩展函数连接MySQL数据库，执行SQL查询语句获取数据。

要连接MySQL数据库并获取数据，可以使用PHP的mysqli扩展或PDO扩展，下面是一个使用mysqli扩展的示例：

1、创建数据库连接

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);
// 检查连接
if ($conn>connect_error) {
    die("连接失败： " . $conn>connect_error);
}
?>

2、编写SQL查询语句

$sql = "SELECT id, firstname, lastname FROM MyGuests";

3、执行查询并获取结果

$result = $conn>query($sql);

4、输出查询结果

if ($result>num_rows > 0) {
    // 输出每行数据
    while($row = $result>fetch_assoc()) {
        echo "id: " . $row["id"]. " Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
    }
} else {
    echo "0 结果";
}

5、关闭数据库连接

$conn>close();
?>

完整代码如下：

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);
// 检查连接
if ($conn>connect_error) {
    die("连接失败： " . $conn>connect_error);
}
$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = $conn>query($sql);
if ($result>num_rows > 0) {
    // 输出每行数据
    while($row = $result>fetch_assoc()) {
        echo "id: " . $row["id"]. " Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
    }
} else {
    echo "0 结果";
}
$conn>close();
?>