mysql 判断数据库是否连接

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

// 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);
} 
echo "连接成功";
$conn->close();
?>

import mysql.connector

try:
    mydb = mysql.connector.connect(
        host="localhost",
        user="username",
        password="password",
        database="database_name"
    )
    print("连接成功")
except mysql.connector.Error as err:
    print(f"连接失败: {err}")
finally:
    if mydb.is_connected():
        mydb.close()

const mysql = require('mysql');

const connection = mysql.createConnection({
    host: 'localhost',
    user: 'username',
    password: 'password',
    database: 'database_name'
});

connection.connect((err) => {
    if (err) {
        console.error('连接失败: ' + err.stack);
        return;
    }
    console.log('连接成功');
});

connection.end();